nxruy Bulletin N? 11. Mt. Radian/, Sithdivisiorv , Westport Division. .Nelson, Land. District
MT. RADIANT SUBDIVISION
JAMES MACKINTOSH BELL
Section on Line BF
— Reference to Geolo g ical Colours
By Authority : John mackay. government Printer.
Argillites, grauwacUes and schists —
Kongahu Series .
I. Breccias, sandstones, gritsj
claystones. and limestones J
2 Soft sandstones, loosely |
consolidated conglomerates > &$Zr&^^'^\
with small lignite seams J | g a y^P-^'l
PROBABLY MAINLY f
PLEISTOCENE. BUTJ Older Debris
IN PART OLDER.AND] Gravel terraces.
IN PART YOUNCER I
[Sea beaches, rive
beds, and terraces...
To urc-inpnny Bulhlu, A'. f 7A Ml .Jtnthuttt Suhihvi.sur, , JYrstporf Jhvi.-iu** .Miaou Lui.d Distri*.
JAMES MACKINTOSH BELL
GEOLOGICAL MAP OF
(MT. radiant subdivision
Scale of Chains
Scads shown thus
Edges of Bush
Ridges arid. Peak*
■ Reference to Geolo g ical Colours and S igns
Argil tites. grauivackes, and schists.
1. Breccias, sandstones, ghts.l
clayatoi.es . and limestones I
2 SoH sondslones, loosely I
IN PART OLDE
IN PART YOUN
Newer Det>r<s. i
Sea beaches, river beds, and terraces 1
LIBRAR1 . /-
YAU'UN I VARSITY
department (of tyM*" \»| of ^Jtines.
NEW ZEALAND GEOLOGICAL SURVEY
(J M. BELL, Director.) '
BULLETIN No. 11 (New Series).
MOUNT RADIANT SUBDIVISION.
EENEST JOHN HEEBEBT WEBB.
ISSUED UNDER THE AUTHORITY OF THE HON. R. McKENZIE, MINISTER OF MINES.
BY AUTHORITY : JOHN MACKAY, GOVERNMENT PRINTER, WELLINGTON.
LETTER OF TRANSMITTAL.
Geological Survey Office,
Wellington, 30th July, 1910.
I have the honour to submit herewith Bulletin No. 11 (new series) of
the Geological Survey.
x The Bulletin deals with the general geology and economic resources of the
Mount Radiant Subdivision, near Karamea, but in the Westport Division, and
was writte'n by Mr. E. J. H. Webb, late Assistant Geologist.
The Bulletin contains 46 pages of letterpress, together with three maps,
and a sheet of sections,
1 have the honour to be,
Your obedient servant,
JAMES MACKINTOSH BELL,
Director, Geological Survey.
Hon. R. McKemde,
Minister of Mines,
Letter of Transmittal
Chapter I. — General Information.
Physiography — continued.
Plan of conducting Work . .
Lakes and Swamps
Settlement and History of Mining . .
The Coastal Plain
Means of Communication
The Upland Country
The Old Land.. ..
Sequence and General Structure of Forma
Detailed Geology — continued.
Igneous Rocks — continued.
C. Intermediate and Basic Igneous Roc!
Mode of Occurrence and Age
Faulting and Warping
Folding and Warping of Tertiary Beds .
Content and Age
Petrology and Description of Speci
Igneous Rocks . .
(1.) Sandstones, Breccias, Grits, an
A. The Main Granitic Intrusives
Occurrence and Age
(2.) Sandstones and Conglomerate
with Small Lignite Seams
Older and Newer Debris
Content and Age
B. Acidic Dykes
Mode of Occurrence
Metalliferous Veins — continued.
Other Occurrences — continued.
Distribution and General Descript
Mount Radiant Reef
General Observations on Metalliferous Vein
New Anaconda Reef . .
Copper Ci'eek Reef
Mount Scarlett Reef . .
Gold and Silver
Lead and Zinc
Suggested Prospecting Operations
Auriferous Alluvial Deposits
( !old Creek . .
Building and Ornamental Stone
ii— Mt. Radiant.
MAPS AND SECTIONS ACCOMPANYING
BULLETIN No. 11.
1. New Zealand, showing Land Districts and Divisions . . . . . . . . . . vi
2. Westport Division, showing Survey Districts . . . . . . . . . . . . vi
3. Geological Map of Kongahu and Otumahana Survey Districts . . . . . . . . 46
4. Geological Sections of Mount Radiant Subdivision .. .. .. .. ..46
By Authority : John Mackay, Govcrnmint Printer.
T A S M A N
SHOWING SURVEY DISTRICTS
Mh.Radicmt Subdivision. (Bulletuv N~?11 )
coloiaed tJais I I
By Authority i Joint Maokay, Qousmmitt Prlnttr.
/OO S./O. +33
BULLETIN No. 11 (NEW 8ERIES).
MOUNT RADIANT SUBDIVISION,
Physiography — continued.
Plan of conducting Work
The Coastal Plain
Lakes and Swamps
Settlement and History of Mining
Means of Communication
The Upland Country
The Old Land . .
The Mount Radiant Subdivision, the geology of which forms the subject of this report, lies
in the extreme north of the Westport Division. It has in the past received practically no
attention from the geologist, previous geological investigation having been confined to a
hurried trip along the coast by Von Haast in I860.*
Upon the discovery in 1906 of copper-bearing veins in the district, a thorough geological
survey of this area was deemed advisable. Accordingly field-work was commenced in March,
1908, and carried on almost uninterruptedly till early in August, 1909. During this period
the writer was assisted in the field-work by Mr. John Mackay, A.O.S.M., who acted in the
capacity of chainman.
The Westport Division lies in the south-west of the Nelson Land District, and is bounded
on the north and south by the Karamea and North Westland divisions respectively, on the
east by the Motupiko and Matakitaki divisions, and on the west by the Tasman Sea. The
area included in the Mount Radiant Subdivision consists of the survey districts of Kongahu
and Otumahana, which form the northern extremity of the Westport Division. It is bounded
* " Topographical and (V logical Explorations of the Western District of Nelson Province, Now Zealand,"
1861, pp. 61, 115, 116.
1— Mt. Radiant.
on the north by an imaginary line running east for a distance of 13 J miles from the mouth of
the Otumahana River. Its southern boundary follows the sinuous course of the mountain-
range from Kongahu Point for a distance of 3| miles, and thence runs due east for a distance
of 16^ miles. Its western limit is the natural boundary of the Tasman Sea, while on the east
it is bounded by an imaginary meridional line 12 \ miles in length, and distant from the coast
13J miles at its northern and 19| miles at its southern extremity. It thus comprises an area
of 195 square miles.
With the exception of a few clearings near the coast, occasional small patches of tussock
country in the river-valleys, and the mountain-tops above the 3,600 ft. level, the entire sub-
division is covered with dense bush.
Plan of conducting Work.
Geological information being, as a rule, derived mainly from rock-exposures on the
mountain-ridges and in the stream-courses, an accurate topographical map is essential to the
carrying-out of a detailed geological examination. Hence, simultaneously with the geological
work, surveys of the streams as well as of the mountain-ranges were undertaken, the former
with compass and chain, the latter by triangulation with theodolite. The results have been
added to the information available from the Lands and Survey Department.
Particular attention was paid to the area in which occurred known outcrops of cupriferous
veins, and every endeavour was made to define the limits of the copper-bearing zone.
The writer desires to acknowledge the assistance given by the Lands and Survey
Department, which supplied the data that formed the basis of the maps, on a scale of
20 chains to the inch, used in the field, and finally of the geological map published with
this report. To Dr. J. S. Maclaurin, Dominion Analyst, and his staff thanks are due
for the careful chemical analyses and assays quoted in this report. The writer would also
express his appreciation of the kind assistance rendered by many of the settlers of Karamea,
Kongahu, and Little Wanganui.
The Mount Radiant Subdivision presents in its western portion a comparatively low-
lying area of " upland country," and in its eastern a mountainous " old land," part of an
uplifted deeply dissected peneplain. The northern half of the coast-line is flanked by a coastal
plain of Recent sediments abutting against the low hills of Tertiary deposits that constitute
the " uplands." These in turn, at a distance of six to eight miles from the coast, abut against
the granitic " old land " of the interior.
The Coastal Plain.
The coastal plain has an average width of about a mile, and is characterized by a broad
swamp lying along its eastern margin for almost its entire length. It has apparently
originated in a sandspit, extending northwards from Little Wanganui Head, that was pro-
duced by the northerly-setting ocean-currents. In course of time the sand-deposits, aided
by the prevailing south-westerly winds and constant additions from the Little Wanganui
River and other streams, advanced shorewards, and finally, connecting with the beach sands,
produced the present coastal plain.
The Upland Country.
The upland country, which near the coastal plain appears in low hills only a few hundred
feet in height, rises gently towards the east, attaining a maximum elevation of about 2,000 ft.
where it meets the " old land." South of the coastal plain the upland country reaches the
coast-line, where it presents a line of cliffs several hundred feet in height that continue
uninterruptedly to the extreme south-west corner of the subdivision.
The Old Land.
The elevated peneplain constituting the " old land " of the interior has now been worn
into a series of roughly parallel ranges, the summit-altitudes of which, while fairly even in a
north and south direction, increase from 4,275 ft. (Mount Radiant) in the west, to 4,950 ft.
(Mount Herbert) just beyond the eastern boundary of the subdivision. The western boundary
of the " old land " is marked by a well-defined fault-scarp that pursues a north-north-easterly
course throughout the subdivision, a direction more or less coincident with that of the main
Of the mountain -ranges into which the old land has been cut the most conspicuous is the
Mount Radiant Range, which maintains a fairly uniform altitude of a little over 4,000 ft., and
is bounded on the west by the fault-scarp already mentioned. Near the centre of the sub-
division it is intersected by the Little Wanganui River, beyond which its continuation appears
in the bold peak of Mount Scarlett (4,100 ft.). To the west of this mountain, and separated
from it by a graben valley a mile-and a quarter in width, the block mountain of Mount Stormy
Range, about 3,500 ft. in height, follows a course parallel with that of Mount Radiant Range
to and beyond the northern boundary of the subdivision. Similarly, in the south, the faulted
block of Mount O'Connor (4,050 ft.), just appearing within the southern boundary of the sub-
division, is separated from Mount Radiant Range by a graben valley about two miles and a
half in width.
In the north-east, the northerly-trending Herbert Range closely follows the eastern
boundary of the subdivision, while towards the centre and south-east the transverse Scarlett
and Allen ranges encircle the heads of the chief drainage-channels of the subdivision.
The cirque-like basins at the heads of many of the streams suggest the possibility of
glaciation as a factor in their formation. Any ice-action, however, that may have taken place
has been slight, and all direct evidence of glaciation has been completely obliterated by sub-
sequent atmospheric denudation.
The most important rivers take their rise near the centre of the " old land," and radiate
in all directions to the boundaries of the subdivision.
The main watercourse is that of the Little Wanganui River, which pursues a more or less
westerly course for a distance of fourteen miles, reaching the Tasman Sea near the centre of
the coastal margin of the subdivision, where it defines the southern limit of the narrow coastal
plain. Where this river flows through the granitic " old land " its channel is narrow, deeply
incised, and frequently gorged, in marked contrast to its broad terrace-flanked course through
the foothill country. Along with Granite Creek in the north and Fall Creek in the south,
this river, with its numerous tributaries, drains the centre and entire western portion of the
subdivision. The north-eastern portion of the subdivision falls within the watershed of the
Kakapo River, a large left branch of the Karamea River, which, rising in the southern end of
the Herbert Range, follows what is probably the line of a fault-fissure in a remarkably straight
course for eight miles, until it reaches the northern boundary of the subdivision. Here it is
joined by the northerly-flowing Huia Stream, which drains the graben between Mount Scarlett
and Stormy Range.
The eastern portion of the " old land " is drained by the headwaters of the Karamea
River, here flowing due east, while the southerly-flowing Johnson and Allen rivers, and other
branches of the Mokihinui River, perform a like function in the south.
1*— Mt. Radiant.
The river-courses within the " old land " are typically gorged, but alluvial flats of some
extent occur in the valleys of Huia Stream, and of Kakapo, Karamea, and Johnson rivers.
Lakes and Swamps.
A few small lakes occur in the subdivision, while innumerable tarns appear near the
mountain-tops, and swamps are common on the low country near the coast. Of the small
lakes, those most worthy of notice are lakes Phyllis and Hanlan. The former lies at an eleva-
tion of 2,190 ft. in a branch of the Mokihinui River in the south of the subdivision. It is a
quarter of a mile long and about 10 chains wide, and has been formed by the damming-up of
the stream by slip matter from both sides of the precipitous valley. That it is shallow and of
comparatively recent formation is shown by the tree-stumps which protrude above the water.
Lake Hanlan drains into Tidal Creek, and, though less picturesque than Lake Phyllis, is
a beautiful little sheet of water nestling among the hills of the uplands. It has a length of
over half a mile, a width of from 6 to 10 chains, and is apparently very deep.
Shag Tarn, at the head of Ponga Creek, is similar to Lake Hanlan, but of smaller size.
Of other sheets of water occurring in the subdivision, the lagoon, over a mile in length,
occurring near the south end of the coastal plain may be mentioned. The large swamp
extending for five miles along the eastern side of the coastal plain covers an area of about
2,000 acres, and has an average width of about half a mile.
Settlement and History of Mining.
Like many other districts in New Zealand, the Mount Radiant Subdivision owed its first
settlement to the enterprise of the gold-seeker. About forty years ago a party of diggers
from Westport, headed by Abbott and McHarrie, found payable gold in the black sand on
the beach north of the Little Wanganui River. After the breaking-up of this party, Abbott,
having elected to take up land on the coastal plain, remained in the district, and thus became
the first settler.
Owing to difficulties of access, settlement was extremely slow, and in 1875 there were only
four settlers who had taken up land along the Kongahu coastal plain. Shortly after, owing to
the discovery of rich patches of alluvial gold in Glasseye Creek, a rush of diggers took place,
followed by some settlement at the mouth of the Little Wanganui River. About fourteen
years ago the fertile flood-plains of the Little Wanganui River attracted the attention of the
settler, while since the commencement of the flax and timber industries in the subdivision
settlement has been steadily increasing, the population at the present date, exclusive of casual
labourers, numbering 114. The main settlement is along the coastal plain, the northern part
of which is known as Kongahu, the southern as Little Wanganui, while the settlement higher
up the river is called Little Wanganui Ferry.
About 1890 some local excitement was caused by the discovery of payable alluvial gold
in Kimberley Creek, a branch of Granite Creek, and about fifty or sixty people participated
in the rush that followed. The rush, however, was of short duration, and the total value of
gold obtained was not more than £2,000. Six years later another small patch of gold was
found by Scarlett and party in Mullocky Creek.
The beach gold that allured the diggers to the district in the early days still affords a
precarious livelihood to a few beach-combers. In February, 1906, the district came into pro-
minence owing to the reported discovery of immense copper-deposits in the mountainous interior.
Two years previously a specimen of quartz carrying appreciable quantities of chalcopyrite,
molybdenite, gold, and silver had been picked up in Silver Creek by Robert Johnson, who
was for some time unaware of the nature of his find. Later on this specimen was assayed,
with results that proved sufficiently encouraging to warrant prospecting operations, which
resulted in the discovery by Johnson and party of the Mount Radiant Reef in Silver Creek.
This find was productive of much excitement in the district, and prospecting operations'
were carried on with great diligence, the outcome being the unearthing later in the same year
of many other outcrops of cupriferous veins, chief among which may be mentioned the New
Anaconda Reef. Almost the entire area over which the outcrops extend was pegged off, and
is now held by three parties — viz., those of Robert Johnson, J. Crabbe, and J. Scarlett. Several
neighbouring areas are held by different parties under prospecting licenses.
In 1907 an option over the New Anaconda Reef was taken up by an Auckland syndicate,
but was allowed to lapse after a little surface-prospecting had been done. The owners have
since been in communication with Australian and foreign firms, but the outcome of their
negotiations has not yet transpired.
Means op Communication.
Communication between the Mount Radiant Subdivision and other parts of New Zealand
is maintained both by sea and by land, although in both cases difficulties are encountered
which render such communication less satisfactory than could be desired.
The mouth of the Little Wanganui River affords a haven suitable for vessels of small
draught ; the bar, which at low tide carries 3 ft. of water, is easily negotiable for such vessels
at high tide. The harbour, however, in common with other harbours on this coast, has the
disadvantage of being impracticable during strong westerly weather, and in consequence the
coastal steamer from Westport, which calls about once a month, is sometimes unable to cross
the bar for days at a stretch. A vast improvement in the harbour could be effected by a
little construction-work on the northern side of the entrance. A mole about 10 chains in
length would suffice to cause the northerly-setting coastal current to carry off the silt which
now tends to block the entrance.
More satisfactory communication can be obtained by connecting with Karamea, which
has, as a rule, a very good steamer service. Karamea Township lies to the north of the sub-
division, and is distant from Kongahu Post-office some five miles by road and bridle-track, or
a mile and a half by water across the Otumahana Estuary.
By land, road and bridle-track compass the twenty-four miles between Little Wanganui
Settlement and Seddonville, the terminus of the railway from Westport. A dray-road starting
from the beach at Little Wanganui Schoolhouse runs inland a mile and a quarter to Little
Wanganui Ferry, whence it proceeds up the valley of Tidal Creek for about two miles. A
bridge is now being constructed over the Little Wanganui at the ferry. A bridle-track, known
as the " Old Inland Road," continues from the end of the dray-road up Tidal Creek Valley,
passes over a low saddle, and goes via Rough and Tumble Stream to Seddonville. From this
track, at a distance of five miles from Little Wanganui Ferry, a bridle-track (the " New Inland
Road") branches off, crosses Happy Valley Saddle, and thence bearing to the south-west,
passes out of the subdivision, eventually connecting with the Westport-Seddonville Railway
near the mouth of the Mokihinui River.
Communication with Mokihinui is also afforded to pedestrians by the " Rocks Road,"
a travel-route eighteen miles in length along the beach from Little Wanganui River. In places
tracks have been made round or over the bluffs, but the route is practicable only at or near low
tide, and travelling along the rough boulder-strewn beaches is decidedly arduous. A con-
nection between Little Wanganui and Kongahu is afforded by the beach, which at low water
forms an excellent roadway for vehicles.
Besides the bridle-tracks already mentioned, others are deserving of brief reference. A
track which connects with the main road to Karamea follows up the course of Granite Creek
for some miles, and passes over a low saddle into the Little Wanganui River, up which it con-
tinues to Belltown. It has a length within the subdivision of about eight miles, and, although
impracticable during wet weather, affords fairly good access to the cupriferous regions of the
subdivision, a well-graded foot-track having recently been made from Belltown to the New
Anaconda Eeef. A well-formed gravel track known as the Wangapeka Eoad follows for a
mile and a half a northerly course from Little Wanganui Ferry along the eastern side of the
big swamp. It then crosses over a saddle into the flood-plain of the Little Wanganui River,
along which it runs, in a more or less easterly diiection, for a mile and a half to near the first
line of bluffs on the river-bank. Little difficulty would be experienced in connecting up the
three miles and a quarter intervening between the end of this track and the bridle-track to
Following down the northern bank of the Karamea River for a distance of two miles and
a half to the eastern boundary of the subdivision is the western extremity of an unfinished
bridle-track that connects with the railway to Nelson at Tadmor. This track is seldom used,
and has been allowed to fall into disrepair. A proposal is now on foot to connect this track
with the one at Belltown, via Little Wanganui Saddle. The plan is quite a feasible one, and
were it carried out the track would afford easy communication between Karamea and Nelson.
The only connection at present is by a rough foot-track passing up the Little Wanganui River
to the hut beyond Kiwi Saddle. Thence a rough blazed track continues over Mount Zetland,
and drops down into the pakihi at the head of the Karamea River, and down this river to
the end of the Tadmor Track.
An easier but much longer connection between the two tracks could be made by following
approximately the course of the foot-track via Lawrence Stream and Saddle (1,600 ft.), and
continuing up the Kakapo River to the saddle (3,080 ft.) at its head, and thence down a small
branch of the Karamea River to the formed bridle-track to Tadmor. This route would have
the advantage of opening up the agricultural land in the Huia and Kakapo valleys.
A bridle-track to connect with the New Inland Road is at present in course of construction
up Glasseye Creek.
Many of the foot-tracks used by early prospectors are now completely overgrown and
lost. A few, however, are still in use, while others have been kept open to some extent by
Where river-beds were found impracticable for the conveyance of camp-equipment and
provisions, it was frequently found necessary to cut foot-tracks through the bush. One of
these runs from the hut on Silver Creek, down Johnson River, for a distance of four miles
and a half, and gives access to the country drained by the Mokihinui and Allen rivers.
Another track, seven miles and a half in length, diverges from the Belltown bridle-track near
the mouth of Lawrence Stream. Passing up this stream it crosses the Lawrence Saddle, and
follows the Huia Stream to the Kakapo River, up which it runs for two miles. Another track
runs south from the Little Wanganui River at the foot of Black Rat to Captain Creek, while
another starts from the same point on the Little Wanganui, and follows the northern bank
of the river to the Wangapeka Track.
The settlers of the Mount Radiant Subdivision are well provided for in regard to tele-
phonic and telegraphic communication, there being three stations in the district — one at
Kongahu, another at Little Wanganui, and another at Little Wanganui Ferry. While the
post-office at Kongahu has a fairly good mail-service dependent on the running of the coastal
steamer to Karamea, postal arrangements at Little Wanganui are not so satisfactory, the
monthly mail-service by coastal boat being supplemented by but one overland mail per month
When cleared, the bushed land of the low-lying portion of the subdivision, especially of
the coastal plain and flood-plains of the various streams, affords a soil productive of excellent
pasturage for cattle. In consequence of this, and of the inducements offered by the Karamea
Butter-factory, the settlers of the district have turned their attention largely to dairy-farming
and cattle-raising. A few sheep are occasionally seen, but are grazed entirely for local con-
Flax grows well in the swampy parts of the subdivision, especially round the margin of
the big swamp on the coastal plain, and for some years flax-milling has been carried on with
a considerable measure of success.
Good milling-timber is to be found throughout the subdivision, particularly on the low-
lying portions. On the coastal plain and in the stream-valleys, particularly those of the
upland area, good patches of red, black, and white pine are of frequent occurrence, while
silver-pine and totara are also encountered. A sawmill has recently been erected near the
mouth of the Little Wanganui River, and has commenced operations with every prospect of
Fruit-growing is another industry that promises well for the future. While in the
mountainous districts the rainfall is very heavy, and snowfalls are frequent during the winter
months, the climate near the coast is exceedingly mild. The district is well sheltered, and
the soil, as a rule, is well adapted for the establishment of orchards.
The Mount Radiant Subdivision is an area which has received very little attention from
geologists or mining engineers, and literature in relation to its geology and mineral resources
is in consequence very scanty. The following short list seems to exhaust all references of
any value : —
1861. Von Haast, Julius : " Topographical and Geological Exploration of the Western
Districts of Nelson Province." Pp. 61, 115, 116. In this is a description of a hurried
trip along the coast, with brief mention of the geology of the coast-line south of Little
Wanganui River, and general remarks on the topography.
1907. New Zealand Mines Record, vol. x, pp. 392, 393 : " The Discovery of Copper at Mount
Radiant." Extracts from a preliminary report by the Director of the Geological
Survey are given.
1907. New Zealand Mines Record, vol. xi, p. 36 : " Applications for Large Areas." Reference
is made to the Mount Radiant district.
1907. C. — 3. New Zealand Mines Department (Annual Report). " Papers and Reports
relating to Minerals and Mining," pp. 7, 8. Reference to discovery and description
of cupriferous reefs at Mount Radiant.
1907. Fry, S. : " Mount Radiant ; a New Zealand Copper Discovery." Engineering and
Mining Journal, vol. 84, p. 1202. A description of the occurrence of copper in
1908. C.-3. New Zealand Mines Department (Annual Report), p. 31. Reference to cessation
of prospecting operations, &c, in the Mount Radiant field.
1908. C.-9. Second Annual Report (New Series) of the New Zealand Geological Survey
Department, pp. 7, 26-31. Short account of reconnaissance and preliminary report
1908. Bell, J. M. : " New Zealand as a Mining Country." Australian Mining Standard,
vol. xl, No. 1046, p. 603. The occurrence of copper and molybdenum at Mount
Radiant is mentioned.
1909. C.-9. Third Annual Report (New Series) of the New Zealand Geological Survey,
pp. 21-23. Contains a summary report of fieldwork in the Mount Radiant Sub-
division during the preceding twelve months. Brief descriptions of the general
geology and of the various mineral occurrences of economic interest are given.
Sequence and General Structure of For-
Detailed Geology — continued.
Igneous Rocks — -continued.
C. Intermediate and Basic
Faulting and Warping
Mode of Occurrence and Age
Folding and Warping of Tertiary
Content and Age
Palaeontology . .
Petrology and Description of Special
(1.) Sandstones, Breccias
A. The Main Granitic Intrusives . .
(2.) Sandstones and Conglome-
Occurrence and Age
rates, with small
Older and Newer Debris
Content and Age
B. Acidic Dykes
Mode of Occurrence
Talus Deposits . .
Sequence and General Structure op Formations.
While the geology of the Mount Radiant Subdivision is on the whole fairly simple, certain
difficulties are presented owing to the entire absence of fossils in the older sedimentary beds
and to the metamorphism to which these beds have been subjected. Faulting has been very
pronounced within the subdivision, and has been productive of various structural complica-
The oldest rocks of the subdivision consist of a series of argillites, grauwackes, and schists,
which, for reasons to be detailed later, have been correlated with the Aorere Series of the Para-
para Subdivision. These beds show considerable folding, and have been involved in the
great fault-movements to which the area has been subjected, and to which they owe their
appearance within the subdivision.
Intruding the rocks of the Aorere Series, and forming the mountain-massifs in the eastern
portion and beyond the southern boundary of the subdivision, are huge bosses of granite that,
together with the Aorere rocks, represent an ancient land-mass reduced by denudation almost
to base-level and subsequently elevated to its present position. Elevation was accompanied
or immediately followed by earth-movements productive of Assuring and tilting of the land-
mass and down-faulting of large areas of country. The granite is penetrated in places by
dykes, both of acidic and semi-basic nature.
Next in chronological order comes a series of sedimentary deposits which, while of later
date than the granitic intrusions, preceded the earth-movements mentioned in the last para-
graph. In places these deposits overlie the rocks of the Aorere Series in marked unconformity,
and there is some reason for believing that they once covered the entire area of the subdivision.
Palseontological evidence shows these strata, which constitute the Kongahu Series of this
report, to be of Miocene age. They are still widely distributed throughout the subdivision,
particularly in the western portion, and have participated in the violent earth-movements to
which the area has been subjected, in consequence of which they show considerable warping,
while in the proximity of the lines of fault they are often sharply flexured and even completely
overturned. They consist of breccias, argillaceous limestones, calcareous claystones, and
sandstones passing up into loosely consolidated gravels, with small carbonaceous seams.
The beds of the Kongahu Series are succeeded unconformably by accumulations of marine,
fluviatile, and other sediments, and of talus deposits, varying in age from Pliocene to Recent.
Although the examination of such a small area as the Mount Radiant Subdivision can
in itself afford little evidence of the geological changes occurring in past ages, the results
obtained bear out to some extent the speculations of those who have carried on geological
investigations in adjacent districts. Little information is available as to the conditions under
which the sediments of the Aorere Series were deposited, since these have but a limited
occurrence within the subdivision, and outcrops are in general poor. An examination under
the microscope of sections of the rocks shows them to consist of fragments of quartz, feldspar,
and ferro-magnesian minerals, evidently the product of disintegration of a granitic land-mass,
subsequently deposited under comparatively shallow-water conditions, such as those prevailing
on a gradually sinking foreshore. No evidence within the subdivision is forthcoming as to
the position of this ancient land-mass, but the generally accepted theory that in early Palaeozoic
times a continental land-mass lay to the west of the present land-area may be considered
probable. After the deposition of the Aorere Series a vast interval of time elapsed, during
which the ancient sedimentaries were uplifted and folded along north-west to south-east
lines, and, as already stated, intruded by huge masses of granite. It is possible that the
intrusions were contemporaneous with or an outcome of the same forces as those that produced
the uplift and folding of the sedimentary rocks. Within the subdivision evidence is entirely
lacking as to the exact age of the granitic intrusions and also of the various oscillations in
level to which the area must, in common with other parts of New Zealand, have been subjected
during this period. It is evident, however, that at the close of this time denudation had
proceeded to such an extent that the land was worn down practically to base-level. Within
the subdivision the early sedimentaiy rocks were almost entirely removed, thus leaving the
granite exposed over a large area. In Miocene times came a period of depression, during
which sediments were deposited to a considerable thickness, probably over the entire area now
represented by land. At or shortly after the close of Miocene times a period of elevation
ensued, followed or accompanied by extensive block-faulting, whereby the general physio-
graphic outlines of the country as at present exhibited were formed.* Following this came a
period of denudation which is still in progress, and during which the more highly elevated
areas of country were almost entirely stripped of their overlying Tertiary sediments.
Elevation continued to early Recent times, but is now probably at a standstill. During
this time slight modifications of the physiographic outlines of the subdivision took place as
a result of denudation, while deposition of sands resulted in the production of the modern
* McKay, "Geology of Marlborough and South-east Nelson," pt. ii, G.S. Rep., vol. xxi, 1802, p. 10.
faulting and warping.
The remarkable outlines of the main physiographic features of the Mount Radiant Sub-
division at once suggest the agency of fault-movements of considerable magnitude. The
general configuration of the country, presenting as it does lofty even-crested mountains
descending abruptly by undoubted fault-scarps to comparatively low-lying areas, leads to the
conclusion that differential earth-movements, by which certain blocks of country have been
elevated relatively to others, have in the past been extremely active. Closer examination
reveals the fact that certain beds of Tertiary sediments developed in comparatively low-
lying parts of the subdivision also make their appearance at higher elevations in the
mountainous regions, while their upturned edges, where they come in close proximity to the
mountain-escarpments, afford further and conclusive evidence of faulting-action.
McKay, in a report on the geology of Marlborough and S.E. Nelson,* draws attention
to the widespread effects of faulting-movements upon the physiography of New Zealand. To
this cause he attributes the existence of several mountain-chains as they appear to-day and
the complete disappearance of the land-mass which at one time lay to the west of the present
land-area.f He mentions the existence of a line of fault — the lower Buller faultj — running-
near the coast between Greymouth and Karamea Bight, and indicates its continuation in a
N.N.E. direction along the coast-line of the Mount Radiant Subdivision.
Another great fault-line, the Takaka-Karamea fault,§ follows an almost parallel direc-
tion beyond the eastern boundary of the subdivision along the upper course of the Karamea
River from its remarkable bend.
The general land-elevation which followed the close of Miocene times was succeeded, or,
more probably, accompanied, by minor subsidences, the general effect being the production
of relatively high and low level blocks. The former now constitute the mountainous areas,
and the latter the low-lying areas of the subdivision.
The high-level blocks are three in number, and are disposed in the north, east, and south
of the subdivision. Of these, the most important is the Mount Radiant Block, which occupies
almost the entire eastern portion of the subdivision. It comprises in all an area of about
seventy square miles, and represents a slightly tilted block with maximum elevation to the
east, its summit-altitudes increasing from 4,250 ft. in the west to 4,950 ft.|| just beyond the
eastern boundary of the subdivision.
The high-level block in the north of the subdivision now appears as the mountain-range
of Mount Stormy, and will be referred to as the Mount Stormy Block. It has a length within
the subdivision of four miles, and an average width of a mile and a half, while it attains a
fairly uniform summit altitude of about 3,500 ft.
Just appearing within the southern boundary of the area under review is the northern
extremity of the high-level block of Mount O'Connor, which rises to a height of 4,050 ft.
The low-level areas of the subdivision may be divided into three blocks, the chief of which
is the upland block, comprising the foothill-area extending from the base of the mountains
to the coast-line. This has a maximum elevation in the south-west, producing in the southern
portion of the block a slight downward tilt to the north-east, which, however, is not noticeable
in the northern portion.
* " Geology of Marlborough and S.E. Nelson," pt. ii, G.S. Rep., vol. xxi, 1892, pp. 1-28. f Lou
cit, pp. 26-28. % Loc. cit, p. 22. § Loc. cit, pp. 21, 22. || Barometric heights.
A second area of relative depression constitutes the graben valley, with an average width
of a mile and a half, lying between Mount Stormy and Mount Radiant blocks. It may be
a continuation of the upland block just mentioned.
The third low-level block, which stands at an elevation of about 1,000 ft. above that
of the others, forms a graben some two miles and a half in width lying between Mount
O'Connor and Mount Radiant blocks.
It is worthy of note that the main fault-lines of the subdivision follow general north-
north-east directions, more or less coincident with those indicated by McKay. What may
be considered the master fault of the subdivision traverses the entire area in a north-north-east
direction near the centre of the Otumahana Survey District. This fault has relative down-
throw to the west of at least 4,000 ft. Its course is marked for a distance of eight miles by
fault-scarps along the western side of the Mount Radiant Range, and further north by the
steep slopes of Mount Scarlett and the northern termination of the Herbert Range. Through-
out almost the entire length of 13| miles the Tertiary strata at the base of the scarps have
been sharply upturned and frequently overfolded. Towards the south, however, the upturn
has been affected and, as it were, captured by a transverse fault along the foot of
Mount O'Connor. This fault runs for a distance of about two miles in an east-north-east
direction along the northern end of the Mount O'Connor Block, and is also well marked by
sharply upturned Tertiary beds along the base of steep scarps.
The main fault-lines of the Mount Stormy Block are roughly parallel with the master
fault of the subdivision. They are connected at their southern end by a transverse fault
half a mile in length. The agency of faulting is again manifested by steep scarps and upturned
Tertiary beds, though on the western side the latter effect is not observable.
Another fault-line of considerable importance extends along the coast-line in a north-east
direction from Kongahu Point to the mouth of the Little Wanganui River, and has evidently
played an important part in shaping the present coast-line. Undoubted evidence of faulting is
exhibited in a granite cliff flanked by upturned Tertiary beds that appears at Kongahu Point,
while the bold escarpments continuing to the Little Wanganui River probably mark the con-
tinuance of the line of fault. North of the mouth of the Little Wanganui River the low coastal
plain conies in, the escarpment retreating inland in an east-north-east direction that possibly
marks a line of minor faulting with downthrow to the north-north-west.
An interesting feature of the Mount Radiant Block is to be observed in the courses of
the rivers and streams dissecting it. These show throughout remarkably straight valleys,
which have a tendency to follow one of two definite directions — namely, from north-north-
west to south-south-east and from north -north-east to south-south-west. These directions
coincide with the master joints of the granite, and it is possible that the river-courses represent
fault-fissures which have followed these lines of weakness — a possibility borne out by the
exceptionally steep side slopes of the valleys.
Farth-lineaments, probably denoting a line of fault at least eight miles and a half in
length, are pres ntcd by the remarkably straight course of the Kakapo River, in line with the
low Kakapo Saddle and a small branch of the Karamea River. Another similar but less
extensive series of earth-lineaments, three miles and a half in length, may also be represented
by the upper two miles of Johnson River, Kiwi Saddle, and Kiwi Creek.
Folding and Warping of Tertiary Beds.
The effect of earth-movements upon the Tertiary beds in the immediate vicinity of the
faults has already been alluded to. The strata are almost invariably folded, tilted at high
angles, and in many cases are completely overturned, while the rocks themselves frequently
show signs of shearing. These extreme effects are usually found close to the granite boundary,
but sometimes extend to considerable distances from tbe fault-line, as in Tidal Creek, where
such phenomena are noticeable to a mile and a half from the line of fault. Further away the
disturbances become less pronounced, rapidly giving place to slight undulations of the strata.
In the relatively depressed area forming the upland country, owing to the combined effects of
tilting and of faulting to the south, east, and north-east, a land of basin has been formed.
Besides marking the boundaries of areas of relative elevation and depression the lines of
fault to some extent form geological boundaries, since it is only in the high-level blocks that
the pre-Tertiary rocks are exposed.
The Aorere Series is but poorly developed within the subdivision, and, as the beds are
entirely without fossils, a definite age cannot with certainty be ascribed to them. They
have, however, been correlated with the Aorere Series of Ordovician age occurring in the
Parapara Subdivision,* on account of a resemblance in lithological characters and because
similar beds, which are probably continuous with the Aorere Series as developed in the Aorere
Valley, are to be found not far to the north and east of the Mount Radiant Subdivision.
Rocks of the Aorere Series within the subdivision are confined to two small areas, the
more important of which lies in the north of the subdivision, on the southern slopes of the
Mount Stormy Range, and is a mile and three-quarters in length by about half a mile in width.
The second area is in the south of the subdivision, on the north-west slopes of Mount O'Connor.
In this case, owing to the steepness of the slope — a fault-scarp — the Aorere rocks have been
much affected by slips, so that good outcrops are not afforded. Occasionally large fragments
of rocks belonging to the Aorere Series were observed as inclusions in the main granitic masses.
Such inclusions occur in Tangent Creek, Allen River, and elsewhere.
The rocks of the Aorere Series have been subjected to considerable folding, which has
taken place along north-west to south-east fines. While this folding may be purely local, and
due mainly to the intrusive action of the granite, it is more probably the result, in part at
least, of widespread earth-movements.
The Aorere rocks consist of argillites and grauwackes, the former frequently meta-
morphosed into schists and phyllites, which are often spotted. As a rule, they show distinct
bedding, the grauwackes being usually in layers from 12 in. to 18 in. thick, separated by
narrower bands of argillite.
Under the microscope, sections of typical argillites show grains of quartz and feldspar
(orthoclase) with large flakes of mica, principally muscovite with minor amounts of biotite,
embedded in a kaofinitic groundmass with grains of magnetite, epidote, and pyrite. The
grauwackes appear to be merely coarser and more siliceous varieties of the argillites, occasion-
ally showing triclinic feldspars and needles of rutile. The schists are more or less silicified.
quartz-feldspar-biotite rocks, with some muscovite, and more or less epidote. Those which
represent the more advanced stages of metamorphism show innumerable dark ovate spots,
with indefinite outlines, probably cordierite. They are invariably crowded with minute
inclusions, and are highly decomposed, altering to fine particles of pinite, magnetite, and
* N.Z.G.S. Bulletin No. 3 (New Series), 1907, p. 20.
A section of a similar rock in the possession of Professor Marshall, Otago University,
obtained from the Anatori River, north of the subdivision, showed well-preserved crystals
of cordierite displaying the characteristic twinning. Fine carbonaceous inclusions and a
little pyrite were also observed in the section.
A specimen from a huge grauwacke inclusion in granite showed, under the microscope,
an exceedingly large amount of sphene. A tendency to segregation among the crystals of
hornblende and biotite was also observed.
Although the folding of the Aorere rocks may have been productive of some amount of
dynamic metamorphism, it is probable that the most pronounced metamorphic effects are of
a thermal and hydrothermal nature, due to the proximity of huge igneous masses, for in no
case have the ancient sedimentaries been exposed at a distance of much more than half a
mile from the intrusive rocks, which again probably underlie them at no great depth.
To the dynamic effects of the granitic intrusions the general schistosity of the ancient
sedimentaries may to some extent be attributable. Hydrothermal action accounts for the
frequent pyritisation and silicification of the Aorere rocks. Thermal action, aided to some
extent by hydrothermal processes, has produced the most striking effects, recrystallization
and metasomatic replacement of the original constituents of the rocks being general. The
formation of mica, both biotite and muscovite, has probably aided in producing schistosity,
and has imparted to the rocks a characteristic sheen, comparable to that seen in North West-
land in similar rocks, also granite-intruded.* In the grauwackes, secondary minerals, as
sphene, epidote, zoisite, and possibly rutile, are common, while amphibole is occasionally
seen. Upon the argilhtes the metamorphic effect is more noticeable, the rocks becoming
highlyJTphyllitic. A mineral, which is probably cordierite, is a frequent product of meta-
morphism. This occurs in indefinite spots, sometimes about a quarter of an inch in length,
but usually much smaller. Epidote and magnetite are of common occurrence.
Acidic plutonic rocks, mainly biotite-granite, have a wide distribution throughout the
subdivision. Dykes of acidic and semi-basic nature are of frequent occurrence within the
granitic masses, but have not been observed in the older sedimentaries. Loose boulders of
a diabasic rock have been noted, but no outcrop in situ was discovered.
A. The Main Granitic Intrusives.
Occurrence and Age.
The acidic plutonic rocks of the Mount Radiant Subdivision appear in the form of huge
bosses, or occasionally as small sills intruding the Aorere strata. Of these rocks there are
three large areas and one small one, which may represent four distinct bosses. It is, however,
much more probable that the various occurrences are connected, the plutonic rocks being
continuous beneath the younger sedimentary beds that obscure their lateral extension.
The granitic rocks, since they intrude the Aorere sediments and are unconformably over-
lain by the Kongahu Series, are post-Ordovician and pre-Miocene in age.
The presence of numerous aplite and pegmatite dykes points to considerable aqueo-
igneous activity within the granitic magma, a condition also indicated by the metamorphic
effects produced upon the Aorere sedimentaries. The almost entire absence of tourmaline,
even from the pegmatites, is a noticeable feature.
* N.Z.G.S. Bull. No. 1 (New Series), 1900, p. 47.
As already stated, four distinct outcrops of granite occur within the subdivision. These
appear in the north, east, south, and south-west of the area, their appearance being due to
relative uplift and subsequent removal of overlying beds by atmospheric denudation. Of
these areas, the most important is that which lies in the east, covering, as it does, the entire
Mount Radiant Block with the exception of a portion in the south-east corner, where a
remnant of the younger beds obscures the granite.
The area next in importance is that of the Mount Stormy Block, in the north of the
subdivision. This, with the exception of the southern portion in which Aorere rocks occur,
consists entirely of granite. The block of Mount O'Connor, just appearing within the
subdivision in the south, forms another important granitic area.
Of considerable significance is the outcrop of granite appearing in the south-west of the
subdivision at Kongahu Point. Here the fact that granite again appears underlying the
younger beds points to the probability of its further continuance beneath these beds through-
out a widespread area.
The usual type of granite encountered in the subdivision is highly porphyritic, with large
phenocrysts of orthoclase, sometimes \\ in. in length, which, on examination, occasionally
show quartz in graphic intergrowth. Finer-textured rocks, however, varying from coarse-
grained granite to felsite, are abundant, and occasionally a gneissic structure is to be observed.
In general the granites are grey in colour, though various shades of pink are common, especially
among the porphyritic varieties.
A microscopic examination shows the general type of rock to be a biotite-granite, but
biotite-muscovite-granite not infrequently occurs, while hornblende-biotite-granite is some-
Biotite-granites. — The biotite-granites (or granitites) are sometimes hght in colour, and
then consist chiefly of quartz and feldspar, with occasional specks of biotite. Usually, how-
ever, the biotite is more in evidence, imparting to the rock a general grey appearance. Some-
times the rock assumes a slightly greenish colour, owing to chloritisation of the biotite. The
feldspar consists of orthoclase, microcline, occasional microperthite, and acidic plagioclase.
Quartz is generally abundant in interlocking grains and plates, often showing strain-extinction.
The biotite generally exhibits fine pleochroism, and sometimes contains needles of rutile.
Magnetite and ilmenite are common, and zircon is occasionally seen. Secondary minerals
are muscovite, sericite, epidote, sphene, zoisite, chlorite, and pyrite.
Biotite-muscovite-granites. — These generally resemble the biotite-granites, except that
muscovite is present, sometimes in large flakes. The muscovite is probably largely secondary,
but some is original.
Hornblende-biotite-granites. — These occur frequently near the head of the Little Wanganui
River, and contain, as a rule, abundant hornblende, generally in minute crystals, but some-
times nearly an inch in length. They are usually much darker than the biotite-granites,
and may represent an intimate mixture of biotite-granite with intrusive diorite.
Gneisses. — A gneissic structure was observed in Piano Creek, Johnson River, Fugel Creek,
and sometimes in connection with the enclosing rock of the cupriferous veins. Microscopic
examination invariably showed the rock to be a crushed and partly recrystallized biotite-
B. Acidic Dykes.
Mode of Occurrence.
As already stated, dykes of aplite and pegmatite are of frequent occurrence throughout
the granitic areas. The aplitic dykes usually appear as bands from 2 in. to 6 in. wide, but
are sometimes in excess of this, the greatest width noted being over 4 ft. The width of the
pegmatite dykes is usually from 1 ft. to 3 ft., but sometimes it exceeds 20 ft. Both aplite
and pegmatite dykes have, as a rule, distinct walls, which more or less coincide in direction
with the master joints of the enclosing granites.
Small well-defined dykes of aplite occur in Kakapo River, Tangent Creek, and Piano
Creek, while less distinct but more extensive occurrences are to be found in the Little Wanganui
River a quarter of a mile above the Belltown Gorge, in Allen River, Huia Stream, and else-
where. Aplite dykes associated with dykes of a more basic nature appear in Drain Creek
half a mile above its mouth, in a small right-hand branch of Johnson River, and at the head
of the Little Wanganui River.
Well-defined pegmatite dykes occur in considerable numbers about the head of the
Karamea River, in branches of Kakapo River, Tangent Creek, and the streams draining the
northern end of the Mount Radiant Range. On the mountain-ranges they occur near the
northern end of the Herbert Range, on the spur south of Mount Zetland, on the ridge over-
looking Tangent Creek, and elsewhere.
In association with dykes of a dioritic nature, pegmatite dykes also occur near the heads
of Huia Stream, Little Wanganui River, and Little Fugel Creek. Special importance attaches
to these dykes, in that in many cases the cupriferous veins of the subdivision are undoubtedly
of pegmatite origin.
The aphte dykes are generally light-coloured, and occasionally have a slight pink shade.
The pegmatite dykes show extremely large crystals of quartz and orthoclase, the latter often
with intergrowths of quartz. The mica is generally muscovite, in plates that are sometimes
an inch in length. Tourmaline in well-formed crystals, up to l^in. in length, was occa-
sionally seen in pegmatitic boulders, but was not observed in situ.
C. Intermediate and, Basic Igneous Rocks.
Mode of Occurrence and Age.
The intermediate igneous rocks of the subdivision appear sometimes as well-defined
dykes, but more frequently have much the appearance of segregations from the main granitic
mass. They consist of diorites and allied rocks. When their dyke character is pronounced,
these rocks, like the acidic dykes, appear to follow more or less the directions of the master
joints of the granite. In width they vary from |in. up to 50 ft., but usually range
from 6 ft. to 8 ft. In no case have they been found penetrating rocks other than the granites.
From their general appearance it is probable that they, like the more acid dyke rocks, were
intruded along the planes of weakness of the granite during the final phases of its intrusion.
It is evident also that the intermediate rocks were, at least in part, intruded prior to the acidic
dykes, for in one case a dioritic dyke 3 ft. to 4 ft. in width, occurring in Tangent Creek about
a mile above its mouth, is cut at a long angle by a 1 ft. dyke of coarse aphte.
The appearance in the field of most of the less acidic rocks would suggest that they were
the result of local segregations from the granitic mass. There are, however, some undoubted
dykes, which have probably had their origin in basic segregations from the magma from which
the granitic mass was derived. Again, the rocks may be of such a nature as to suggest a basic
intrusion into a still liquid acidic mass, with a consequent intimate mixing of the two rocks.
While basic igneous rocks are widely distributed throughout the granitic areas of the
subdivision, well-marked dykes occur in only a comparatively few instances. The most
important of these appear in the headwaters ofjiKakapo and Little Wanganui rivers, in Tangent
Creek, in Fugel Creek, Little Fugel Creek, and in other branches of Johnson River.
Megascopically the intermediate rocks of the subdivision are usually fine-grained, holo-
crystalline, and almost black in colour. Under the microscope the structure is generally
typically plutonic, even in the cases of many of the small dykes, a fact which points to their
intrusion into a still uncooled mass. Occasionally, however, a structure more typical of a dyke
rock was observed. The rocks are usually acidic diorites. Sometimes a syenitic phase is
observed, and frequently a transition to hornblende-biotite-granite is encountered, while in
one case a diabasic rock with camptonitic structure was noted.
Diorites. — -The diorites consist largely of feldspar, generally an acidic plagioclase. Green
hornblende, usually highly chloritised and serpentinised is, as a rule, abundant, while plates
of biotite are of less frequent occurrence. Magnetite, ilmenite, sphene, and occasionally pyrite,
are also present.
Syenites.— Rocks displaying a syenitic facies show under the microscope orthoclase,
hornblende, and biotite, with minor quantities of muscovite, quartz, magnetite, ilmenite,
Content and Age.
For lithological and palseontological reasons, the sediments which were laid down during
the Tertiary subsidence may be divided into two formations, —
I. Lower Kongahu Formation. — Sandstones, breccias, grits, and limestones.
II. Upper Kongahu Formation. — Soft sandstones and loosely consolidated conglomerates,
with small lignite seams.
The name " Kongahu Series " has been applied to these strata owing to their full develop-
ment in the Kongahu Survey District.
As a general rule, the various members of the series are well exposed throughout the
subdivision. Occasionally the Upper Kongahu beds have been removed by denudation,
while in some cases members may have been originally lacking or may be represented only
in a slight degree.
The examination of the fossil-contents of the Kongahu beds has assigned to them a
Miocene age. The Lower Kongahu Formation may be correlated with the Oamaru Series of
Lower Miocene age, while the Upper Kongahu Formation corresponds with the Pareora beds
of Upper Miocene age. For the present, however, it has been considered advisable to treat
the two formations as one series. The entire thickness of these beds within the subdivision,
as will be seen later, is at least 3,500 ft. to 4,000 ft.
Rocks of the Kongahu Series have a very wide distribution throughout the subdivision,
and cover more than half the entire area. With the exception of the mountain-blocks of
mounts Stormy and O'Connor, the whole of the area west of the main fault-line of the sub-
division contains rocks of the Kongahu Series, though these are frequently mantled by younger
rocks. Again, in the south-east corner of the subdivision, members of this series appear over-
lying the igneous rocks at considerable altitudes.
Reference to the map will show that the Lower Kongahu Formation has its maximum
development in the south-west of the district, but continues northward throughout the sub-
division as narrow belts along the bases of the main fault-scarps. The production of these belts
has been brought about by the dragging-up of the Tertiary beds along the various lines of
fault. The most prominent belt follows along the foot of the main fault-scarp from the
northern boundary to about three miles from the southern boundary of the subdivision.
Along this line it varies in width from less than 300 ft. to over half a mile. The belt then
widens out and extends westward, its northern boundary describing a semi-circle, eventually
terminating at the fault-line near the mouth of the Little Wanganui River. Its eastern
boundary continues south along the Mount Radiant fault-line. The sudden increase in width
of the exposure in the south of the subdivision is due to the fact that, except along its northern
margin, where they are steeply inclined, the Lower Kongahu beds are disposed at compara-
paratively low angles, while the Upper Kongahu beds have been completely removed by
Another belt of Lower Kongahu rocks, about five miles in length, and having a width
varying from 100 ft. to 1,000 ft., follows along the foot of Mount Stormy Range, on its eastern
and southern sides.
In the south-east corner of the subdivision members of the Lower Kongahu Formation
are exposed over an area three miles in length and one mile in width. The beds are evidently
the remnant of strata that at one time, in all probability, overspread the entire surface of the
In the north of the subdiv sion, where exposed in the bed of the Kakapo River, the Lower
Kongahu Formation shows a thickness of about 1,800 ft. In the south-west of the subdivision
a thickness of at least 1,500 ft. is exhibited, the beds being exposed continuously from sea-
level to the top of the hill on which Trig. Station K (1,503 ft.) is situated.
Members of the Upper Kongahu Formation are exposed throughout the remaining por-
tion of the upland country, though in places they are obscured by recent debris. The thick-
ness of this formation is probably not less than 1,600 ft., and may be much more.
Reference has already been made to the pronounced effects of the faulting-movements
upon beds of the Kongahu Series. While it is possible that other movements may have
affected these beds, it is undoubtedly the case that the main structural effects have been pro-
duced in connection with the orogenic movements alluded to.
As a rule, the tendency of each fault has been to bring about a monoclinal upf old of the
Tertiary rocks along the margin of the relatively down-faulted block. A simple combination
of two such folds, roughly parallel, has produced a synclinal structure in the graben east of
Mount Stormy Range. Further south, the steep folds along the mountain-bases, with the
gentle easterly tilt of the upland block, combine in the production of a basin the north-westerly
portion of which is wanting.
The northern portion of the upland area appears to have been much less affected by the
faulting-movements than the southern and eastern portions ; and the Kongahu beds are here
generally horizontal, though occasional instances of local folding are encountered. Along
the western margin of Mount Stormy Block outcrops of Tertiary rocks are few, the beds being-
obscured by heavy overburden from the mountain-slopes. Such outcrops as appear, how-
ever, are those of the younger members of the series, and afford no evidence of having been
affected by fault-movements.
The sharp folding to which the Tertiary beds have been subjected during the faulting-
movements does not, as a rule, extend more than a mile from the line of fault. Generally
the distance is much less, but in the south of the area it sometimes reaches a mile and a half.
Beyond this limit the folding rapidly lessens in intensity, and gentle undulations of the strata
Moderate easterly and north-easterly dips, usually at angles of from 10° to 20°,
characterize the Kongahu beds in the south-west of the subdivision.
The high-level Tertiary strata in the south-east corner of the subdivision have a north-
easterly dip of about 16°, probably due to local tilting of a portion of the Mount Radiant Block.
In the area forming the graben between Mount O'Connor and the Mount Radiant Block
the effects of upturn along the lines of fault are not observable, the beds having a fairly regular
dip ranging from 20° to 30° towards the east and north-east.
2— Mt. Radiant.
In the beds of the Kongahu Series fossil shells are, in places, found in abundance, occasional
indefinite leaf-impressions occur, and in certain beds fucoid casts are frequently seen. The
following is a list of fossils collected by the writer, and classified by Mr. E. de C. Clarke, of
the Geological Survey Staff : —
Upper Kongahu Formation.
Schizaster rotundatus. Dentalium giganteum.
Cucullcea ponderosa. Natica ovata.
Glycimeris globosus. Struthiolaria senex.
Cardium spatiosum. Buccinum robinsoni.
Corbula dubia. Siphonalia dilata.
Chione vellicata. Nucula (sp.)
Dosinia grayi. Also carapace of crab.
Lower Kongahu Formation.
Magellania parki. Scalaria lyrata.
Magellania sufflata. Turritella rosea (?)
Pecten beethami. Ostrea (sp.).
Amussium zitteli. Also vertebra, apparently of shark.
A boulder of calcareous sandstone from the Upper Kongahu Formation contained a block
of petrified wood which, on microscopic examination, proved to be a species of Podocarpus.
Several specimens of a large and hitherto undescribed brachiopod were found in beds of
the lower formation on the beach south of Little Wanganui River.
To this shell the name Magellania magna has been given by Mr. A. Hamilton, of the
Dominion Museum, Wellington, to whom the writer is indebted for the following descrip-
tion : —
Magellania magna, n. sp.
Shell generally suborbicular, but having a considerable range of form.
Test thick with a smooth surface in the best-preserved specimens, with well-defined
growth-lines and close fine punctation.
Peduncular valve very convex in a longitudinal direction, but the transverse convexity
is flattened. Ventral valve much less convex.
Beak strongly incurved, and slender for the size of the shell. The foramen in the
only well-preserved example is large and complete.
Deltidium apparently rather small.
Measurements : Length, 90-60 mm. (3|-2| in.) ; width, 97-75 mm. (3|-3 in.) ; depth,
50-40 mm. (2-l£in.).
Magellania magna, according to the eight specimens submitted, is a larger species and
more orbicular than M. sufflata of Tate,* or M. novara, Ihering, and is from beds apparently
not synchronous with the limestone of the Weka Pass.
Microscopic sections of rocks from the Lower Kongahu Formation reveal the presence
of sponge spicules, at least one species of Radiolaria, and many genera of Foraminifera, among
which may be mentioned Rotalia, Cristellaria, Nodosaria, Globigerina, Mihola, Textularia,
and Dentalina (?).
Petrology and Description of Special Areas.
The beds of the Kongahu Series, as previously stated, consist of —
(1.) Lower Kongahu Formation — Sandstones, breccias, grits, and hmestones.
(2.) Upper Kongahu Formation — Sandstones and conglomerates, with small lignite seams.
*Tate, Trans. Phil. Soc. of Adelaide, 1880, p. 18, pi. vii, fig. 3 ; and pi. yiii, fig. 4. See also Hutton, Trans.
N.Z. Inst., vol. xxxvii., pi. 46, fig. 1.
(1.) Sandstones, Breccias, Grits, and Limestones.
These beds are of marine origin, and represent the earliest deposits during the Miocene
subsidence. The physical characters of the various members point to slight oscillations in the
height of the coast-line during their deposition, while there is a general tendency for the con-
stituent particles to become finer in grain from west to east.
These beds are found unconformably overlying those of the Aorere Series in Limestone
and Tidal creeks, while at Kongahu Point, in the Mokihinui River, Harvey Creek, and else-
where, contact with underlying granite is to be observed.
The lowest member of this formation is an arkositic rock, sometimes calcaTeous, varying
in texture from a coarse grit to a fine-grained sandstone. The finer-grained varieties are
generally argillaceous, and those appearing in the Mokihinui River are sometimes carbon-
aceous, and frequently show pyritic nodules an inch in diameter, while marine fossils are of
common occurrence. The coarser-grained varieties appear in Kakapo River and Harvey
Creek, and are generally dark in colour, owing to the large amount of biotite which they con-
tain. The rock itself consists of particles of quartz, feldspar, and biotite, the product of
disintegration of a biotite-granite. These materials have accumulated as littoral deposits,
and are in some cases cemented by carbonate of lime.
Following the arkositic sandstones, comes a series of more or less calcareous feldspathic
sandstones, grits, and breccias, with highly argillaceous limestones, the whole having a thick-
ness of at least 1,500 ft.
The sandstones, grits, and breccias are best exposed along the coast-line south of Little
Wanganui River, where escarpments several hundreds of feet in height appear continuously
for five miles and a half.
The argillaceous limestones have their maximum development in the upper part of the
formation. They frequently grade into calcareous sandstones and claystones, and often
emit a distinct odour of petroleum.
A noticeable feature of the Lower Kongahu beds, as developed along the coast-line, is
the frequent occurrence in them of isolated fragments of granite, generally from 3 ft. to 4 ft.
in maximum diameter, but sometimes much larger, giving the beds somewhat the appearance
of glacial deposits. Since these occurrences are confined to the coast-line, it is possible that
this marked the precipitous coast-line of a granitic land which during the early part of the
Miocene subsidence lay to the west of the present land-area. This is further borne out by the
breccia beds, which probably represent beach accumulations at the base of a granitic cliff.
The argillaceous limestones, with which may be included their varieties, the calcareous
claystones and sandstones, are the most widely distributed of all the members of this forma-
tion. In colour they are usually light-grey to buff on weathered surfaces, but slaty-grey
on fresh fracture-faces. They are frequently somewhat micaceous, and often show calcite
in veinlets and along shearing-faces. The limestones and calcareous claystones are generally
tough and compact, breaking often with conchoidal fracture, and where weathered to any
extent present very slippery surfaces. As a rule, the finer-grained varieties contain numerous
fucoid-remains, but other fossils are rare. The coarser varieties, however, especially those
on the coast-line, are highly fossiliferous.
The beds of grit appearing on the coast-line, and occasionally encountered elsewhere in
the subdivision, consist of quartz particles more or less rounded, and averaging about | in. in
diameter, embedded in a matrix of fine quartz and feldspar grains, in which occasional flakes
of muscovite appear. The beds are frequently fossiliferous, and sometimes highly calcareous.
The breccia beds consist of accumulations of more or less angular boulders, and smaller
fragments and pebbles of biotite-muscovite-granite, and sometimes of schist, with occasional
fragments of claystone and grit in a sandy calcareous matrix. They represent, as previously
stated, littoral deposits near a precipitous coast-line. Sometimes the cementing matrix is
2*— Mt. Radiant.
almost entirely absent, so that the beds assume much the appearance of surface deposits ;
again, only occasional boulders will be found in a bed of grit or sandstone.
In the exposures on the coast-line the included rock-fragments vary in diameter from
a fraction of an inch to over 16 ft., though in general they average 3 ft. to 4 ft. in diameter.
In corresponding beds exposed in the Kakapo River, the rock-fragments are much smaller,
the maximum diameter recorded being 4 in. The beds here are only a few inches in thickness,
and much resemble surface accumulations.
The granite forming the majority of the larger constituents is usually porphyritic
in structure, but finer-grained varieties are frequent.
The uppermost member of the Lower Kongahu Formation is a well-defined bed of lime-
stone, extending for miles throughout the subdivision. This bed of limestone usually has a
thickness of about 20 ft., but sometimes expands to 40 ft. or 50 ft.
The limestone is evidently a shallow-water deposit, and is generally of a flaggy nature, the
individual bands averaging from 4 in. to 6 in. in thickness. It is usually more or less shelly,
is generally arenaceous, and sometimes argillaceous or glauconitic. In places, however, bands
of excellent quality occur. These are often bluish in colour, again almost white, and some-
times speckled with biotite and rarely with pyrite. The high-grade bands are often visibly
crystalline or semi-crystalline.
In many cases the limestone is inclined to be a calcareous grit ; again, angular fragments
of quartz and feldspar, a quarter of an inch in diameter, may be scattered through it, while
again some of the bands may consist of conglomerate with calcareous matrix. In some cases
the hmestone may grade into the underlying highly argillaceous limestones and calcareous
claystones, but as a rule the dividing-line is well marked. Fossils are abundant, especially
in the more arenaceous varieties.
The beds in which bands of conglomerate occur are exposed in the track-cutting at the
southern flank of Mount Stormy Range. The pebbles average about 2 in. in diameter, and
consist for the most part of soft micaceous schist, with minor quantities of biotite-granite,
schistose argillite, quartz, and feldspar.
Under the microscope the constituent minerals of most of the Lower Kongahu rocks
are seen to be identical, and to vary only in degree of comminution and in the proportions
in which they are present. They consist essentially of grains of quartz and feldspar (ortho-
clase, microcline, and acidic plagioclase), with flakes of biotite and muscovite embedded in a
matrix, generally of calcite, but in the fine-grained varieties of kaolin with more or less calcite.
GUauconite is frequently present, with occasional chlorite, magnetite, and pyrite. In some of
the more calcareous rocks fragments of shells, Radiolaria and Foraminifera, occur. The rocks
are thus to a great extent disintegration-products from a granitic mass, that have accumu-
lated as littoral deposits.
(2.) Sandstones and Conglomerates, with Small Lignite Seams.
The Upper Kongahu Formation consists of fine-grained, usually calcareous, sandstones,
probably at least 1,600 ft. in thickness, followed by beds of coarse sandstone and con-
glomerates, which contain small seams of impure lignite, and attain a maximum thickness
of about 600 ft. The fine sandstones of this formation are the most widely distributed of
all the Kongahu rocks, and cover a very large portion of the upland country.
The coarser beds of the formation are disposed along the low hills bounding the coastal
plain, and extend inland for about a mile. It is possible that these beds were laid down con-
temporaneously with some of the finer-grained sandstones deposited further to the east.
The beds, except where disturbed by faulting-movements, are usually horizontal or
slightly undulatory, though marked local flexures are occasionally to be observed.
The fine-grained sandstones characterizing this formation are generally light bluish-grey
in colour, though sometimes much darker. As a rule they are soft and micaceous, or occasion-
ally argillaceous. Frequently hard calcareous bands from 4 in. to 1 ft. in thickness make
their appearance. Shelly bands from 5 in. to 18 in. thick are occasionally met with, and in
one instance an interstratified band of shelly conglomerate was noted. Bedding-planes,
except where the calcareous bands occur, are usually very indistinct, but occasionally are
indicated by lighter-coloured laminae. Where folding of the beds has taken place, the more
calcareous and argillaceous bands are frequently brecciated, sheared, and slickensided, the
fracture spaces being filled with calcite. Throughout these beds fossils are of frequent occur-
rence, while in the more calcareous bands concretions are common.
A megascopic examination of an average specimen of the Upper Kongahu sandstone
shows an intimate mixture of fine rounded grains of quartz and feldspar, with minute flakes of
muscovite. Under the microscope a calcareous matrix, with numerous Foraminifera, is
observed, and the feldspar is seen to consist of orthoclase, with minor amounts of microcline,
andesine, and perhaps other acidic plagioclases.
The following is an analysis of an average specimen of the fine-grained calcareous argil-
laceous sandstone : —
Silica (Si0 2 ) . . . . . . . . . . . . 44-05
Alumina (A1 2 3 ) . .
Ferric oxide (Fe 2 3 )
Lime (CaO )
Carbonic anhydride (C0 2 )
Water and organic matter
Alkalis and undetermined
A single bed of conglomerate from 9 in. to 18 in. thick, interbedded with the fine-grained
sandstones, occurs in Ray Creek. The inclusions consist of well-rounded pebbles, averaging
about 1 in. in maximum diameter, of quartz and schistose argillite, while shell-fragments are
abundant. The quartz is usually creamy white, but sometimes almost black. The argillite is
laminated and highly micaceous. Granite pebbles are entirely absent.
The conglomerates and sandstones forming the younger members of the Kongahu Series
represent beach deposits, generally very loosely consolidated. The sandstones, though as a
rule coarse-grained, in many places show finer kaolinitic bands with occasional small seams
of impure lignite. The lignite is evidently a swamp deposit, and indicates the probable exist-
ence near the close of Miocene times of conditions similar to those obtaining on the coastal
plain at the present time.
The conglomerates consist of pebbles of grauwacke, quartz, and granite in a sandy matrix.
Grauwacke predominates, in pebbles usually averaging 2 in. in diameter. Quartz is next in
abundance, while biotite-granite occurs only in minor quantities. The conglomerates
occasionally carry light colours of gold.
Outcrops of lignite showing two distinct seams, each averaging 1 ft. in thickness, occur to
the north of the subdivision. The continuance of these seams within the subdivision is indi-
cated by the presence of fragments of lignite in the beds of the small streams draining into the
big swamp of the coastal plain.
The Kakapo River in its course cuts through the upturned beds of the Kongahu Series,
thus affording a very good natural section of these rocks. For a distance of a mile and a
quarter from the confluence of this river with the Huia Stream, beds of soft sandstones, repre-
senting the Upper Kongahu Formation, outcrop in synclinal arrangement. These are followed
by beds of the lower formation, consisting of 50 ft. of limestone, 1 ,800 ft. of claystone, and
50 ft. of arkose, beyond which the basement granite appears. Occasional thin beds of cal-
careous grit and breccia occur with the claystones, and all the beds are steeply inclined, or, in
places, even vertical. A somewhat similar section is afforded by Limestone Creek, except that
here the basement rocks are Aorere sediments.
OLDER AND NEWER DEBRIS.
Content and Age.
Deposits of debris derived from the sedimentary and igneous rocks described on the
preceding pages occur in many parts of the subdivision.
Since the close of Miocene times, when elevation of the land exposed the Tertiary and
older rocks to the effects of subaerial denudation, accumulations of debris have been in process
of formation, and in many cases are still being added to. In consequence it is impossible to
define the boundaries between deposits of Pliocene, Pleistocene, and Recent age.
Deposits of older and newer debris occur on the low coastal plain, along the present coast-
line, and in the flood-plains and courses of the various streams and rivers of the subdivision.
They also occur along the base of the mountain-scarps, in many places on the mountain-slopes,
and in the beds of the lakes and swamps of the subdivision. They thus constitute accumula-
tions of marine, fluviatile, estuarine, lacustrine, swamp, and talus materials, and, as such, may
be briefly discussed.
Except along the southern part of the coast-line, the modern littoral deposits are usually
fine-grained, and consist of sands and muds, coarser particles having been generally deposited
in the stream-beds some distance from the coast. Along the coast-line south of the Little
Wanganui River coarser deposits are in evidence, these being derived from the Miocene
breccias and from granitic cliffs further to the south.
The low coastal plain extending north of the Little Wanganui River consists of sands
deposited originally as a sandspit by the northerly-setting coastal currents. With these
sands are muds brought down by the various streams now entering the swamp.
With the sand of the beach bordering the coastal plain are associated leads of black sand
(magnetite), in which gold occurs.
Recent fluviatile deposits appear in all the stream-beds of the subdivision. They con-
sist usually of boulders and cobbles of granite, with minor amounts of Tertiary rocks, and
occasionally of Aorere argillite.
The flood-plains and terraces of several of the streams and rivers show gravel-deposits
considerably older than those just mentioned, while still more ancient river-debris is occasion-
ally found overlying the Tertiary rocks at higher altitudes. Of these last beds, which are
somewhat auriferous, only remnants are found, denudation having, as a rule, entirely removed
Fluviatile sediments, probably deposited by the Karamea River in ancient times, are seen
overlying the upper beds of the Kongahu Series about the Karamea Initial Trig. Station in
the north of the subdivision. They here appear to rest conformably upon the older beds,
but unconformity is shown further north beyond the limits of the subdivision, where the beds
attain a considerable thickness.
Estuarine deposits are represented by the fine sands and muds accumulating in the Otu-
mahana Estuary, in the extreme north-west of the subdivision. They are also to some degree
represented in the beds forming the coastal plain.
Beds of lacustrine deposition are of small extent, being confined to accumulations of
soft sediments in the basins of Lake Hanlan and Lake Phyllis, and to|a less extent in those
of the numerous mountain-tarns.
Deposits of peat with fine muds, and often with hydrous iron-oxide, characterize the large
swamp of the coastal plain. In the smaller swamps similar conditions prevail, though much
less in degree.
Screes of small extent are frequently encountered on the mountain-slopes, while immense
accumulations of granitic debris, due chiefly to slips from the slopes above, occur along the
base of the ranges, particularly where fault-scarps are visible.
Metalliferous Veins — continued.
Metalliferous Veins . .
Other Occurrences — continued.
Distribution and General
General Observations on Metalliferous
Mount Radiant Reef
New Anaconda Reef
Copper Creek Reef
Mount Scarlett Reef
Gold and Silver
Mackay's Reef . .
Lead and Zinc
Crabbe's Reef . .
Suggested Prospecting Operations . .
Auriferous Alluvial Deposits
Building and Ornamental Stone
The Mount Radiant Subdivision presents features of economic interest not only from
a geological, but also from an agricultural and pastoral, point of view.
In the wooded flood-plains of the watercourses of the subdivision, especially those of
the upland country, considerable stretches of fertile land are still lying idle. This. land, when
cleared, will provide good pasturage for cattle, while the grassed summits of the mountains
would, if rendered accessible by proper tracks, afford suitable grazing for sheep, except during
a few months in the winter. Swampy land, which, if drained, would be adapted for flax-growing,
occurs in the low-lying areas near the coast.
Valuable timber is found throughout the subdivision, particularly along the water-
courses of the upland region, while water-power is afforded by the streams descending from
the highlands. In this last connection attention is called to the natural reservoir of Lake
Hanlan, which has a discharge, under ordinary conditions of rainfall, of about three heads
of water. The capacity of this sheet of water, which stands at an elevation of 295 ft.* above
sea-level, could be readily increased to an enormous extent by a dam across its gorged outlet.
Owing to its proximity to Little Wanganui Ferry, Lake Hanlan offers to the settlers of that
district a very convenient source of water-power.
It is, however, with the possible mineral products of the subdivision that this report is
most concerned. The occurrences of these may be considered under the headings of metal-
liferous veins, auriferous alluvial deposits, limestones, lignite, petroleum, and building
and ornamental stone.
Distribution and General Description.
Throughout the Mount Radiant Subdivision metalliferous veins are encountered only
within the granitic rocks, and are confined to a zone of country a mile and a quarter in width,
extending along the western edge of the Mount Radiant Block. In this zone, again, they
* This and other heights mentioned in this chapter are barometric.
have their maximum development in an area four miles in length, extending in a northerly
direction from the confluence of Fugel Creek with Johnson River to a little beyond Mount
The veins frequently appear to be of pegmatitic origin, and vary in width from a few
inches to over 20 ft. In direction the strike of the veins seldom exceeds 45° on either side
of the meridian, while in the majority of cases it is N.N.E. or N.N.W. — directions coincident
with those of the master joints of the enclosing granite. The dip is usually very steep, and
Rarely can the veins be traced along their strike for any considerable distance. It is
highly probable that in some cases at least they are lenticular in shape, pinching out rapidly
both in vertical and in horizontal extension. On the other hand, it is possible that certain
outcrops will eventually prove to be connected, thus forming continuous vein-systems. This
could be ascertained by systematic surface-trenching, and in this connection there is ample
scope for further prospecting.
Sometimes well-defined walls are present, but more commonly one or both may be
indefinite, the vein being greisen-like, while, again, it may exhibit a mass of reticulating vein-
lets almost of the nature of a stockwork. The vein-material is, in the first case, usually quartz
alone. In the second case, while quartz is the main gangue-matter, mica is or has been present,
and some unaltered feldspar may occur. In the third case feldspar is frequently present
with the quartz, and mica is occasionally seen, whilst the rock between and near the veins
may also carry values.
Enlargement of the veins by metasomatic replacement of the wall-rock with ore is in
many cases observable.
The metalliferous constituents of economic importance are generally copper compounds,
of which the sulphide chalcopyrite is most general. Other copper-sulphides sometimes present
are bornite, chalcocite, and covellite ; while, of the oxidation-products, melaconite is of
frequent occurrence, and cuprite, malachite, azurite, and chrysocolla are sometimes
encountered. Owing to rapid denudation the oxidized zone is seldom of any considerable
depth. The cupriferous minerals generally appear in streaks and bunches filling fracture
spaces in the vein-material, but are sometimes disseminated throughout the gangue.
Occasionally copper-sulphides may be observed associated with, and possibly replacing, the
ferro-magnesian constituents of the enclosing rock.
Pyrite is usually present in greater or less amount, and is occasionally the sole metal-
liferous constituent of the ore.
Molybdenite is almost invariably associated with the copper minerals, and sometimes
has crystals of chalcopyrite finely disseminated through it. As a rule, it occurs in slicken-
sided coatings on cleavage faces, or as veinlets about a quarter of an inch and sometimes nearly
half an inch in width, filling fracture spaces in the vein-material. Occasionally it appears
finely distributed throughout the gangue, and in some cases it probably replaces to some
extent the mica of the greisen-veins.
Gold and silver are almost invariably present, generally in very small amounts, and are
probably to a large extent associated with the pyrite present in the ore.
Lead and zinc sulphides sometimes occur, and in one instance scheelite is said to have
It is evident from the appearance of the ore that the metalliferous constituents are to a
large extent, and possibly in some cases entirely, of a secondary nature, having been deposited
subsequent to a Assuring of the vein-material. This deposition may have been effected by
solutions ascending from a heated magma. On the other hand, it is possible that it may have
been produced by descending meteoric waters acting on original metalliferous constituents
of the ore, the portions of the veins now exposed representing part of the zone of enriched
sulphides. In the latter event it may be expected that the ore will become poorer in depth,
but prospecting operations are not sufficiently advanced in any instance to show if this is
From the above remarks, it will be seen that the cupriferous veins of the Mount Radiant
Copper-field bear a striking resemblance to those of Butte, Montana, where sulphide ores occur
in a granitic rock, replacement of which by the vein-material is of general occurrence.* In
other ways they resemble those of Eastern Maine, where molybdenite occurs in pegmatitic
dykes that penetrate granite.f
Mount Radiant Reef. — The Mount Radiant Reef outcrops at an altitude of 2,950 ft. in
the bed and on both banks of Silver Creek, about 50 chains east of the Mount Radiant
Trigonometrical Station. On the north bank of the stream the vein-formation is exposed
continuously for 150 ft., and again in a small left-hand tributary, while indications of copper
found in Silver Creek for a distance of 5 chains above the main outcrop show the widespread
nature of the mineralisation of the country in this locality.
Prospecting operations, which have been confined to the construction of a small drive 9 ft.
in length on the northern bank of the stream, and to some surface-work vertically above the
drive, and elsewhere, are sufficient to satisfactorily exhibit the nature of the vein-formation.
This has a width of at least 66 ft., and consists of a series of more or less parallel veins from
4 in. to 3 ft. in width, with small irregular ramifying veinlets, the whole presenting somewhat
the appearance of a stockwork.
Owing to the nature of the outcrop, its strike and dip are difficult to determine, and,
though the individual veins have a more or less north-easterly strike, indications point to a
general N.N.W. trend for the whole formation.
The veins appear to be of pegmatitic origin, and in places pass into typical pegmatite.
The enclosing rock is a biotite-muscovite-granite.
The vein-material consists principally of quartz, though light-pink feldspar is very
common, sometimes appearing as veinlets 2 in. to 3 in. wide, and flakes of muscovite are of
occasional occurrence. The quartz is frequently somewhat vitreous and splintery, and is
white in colour.
Of the metalliferous constituents of the ore, molybdenite is the most conspicuous, but
chalcopyrite is general, whilst a little bornite and stains of malachite and chrysocolla are
occasionally seen. Pyrite is of common occurrence, and melaconite and molybdite some-
Molybdenite generally occurs along shear-faces and filling fracture spaces in veinlets,
sometimes from 2 ft. to 3 ft. in length and up to half an inch in thickness. It also appears
in spots and small bunches throughout the vein-material as well as in the wall-rock. While
often associated with the pink orthoclase, it is by no means confined to the feldspar-gangue.
It is sometimes much shckensided, showing that movements have continued within the vein
subsequent to the deposition of the molybdenite.
Chalcopyrite, sometimes coarsely crystalline, occurs in bunches and stringers, filling
fracture spaces, but is also often finely disseminated throughout the vein stuff and the country.
The other sulphides of copper, which are probably secondary products, are usually associated
with the chalcopyrite, as is also pyrite.
The prospecting-drive exposes three veins, the most promising of which is at the entrance,
and is 2 ft. 8 in. in width.
* Kemp, J. F. " Ore-deposits of U.S.A. and Canada," pp. 196-203.
f U.S. Geolog. Survey Bull. No. 260, p. 197-
Samples from various parts of the vein-
assayed as follows : —
(1.) Country rock from face of drive
(2.) Vein near end of drive
(3.) Country rock between first and second
(4.) Vein at entrance to drive
(5.) Exposure above mouth of drive
Oz. dwt. gr.
2 8 13
More detailed analyses were made of samples (2), (4), and (5), as follows :-
Molybdenite (MoS 2 )
Cuprous sulphide (Cu 2 S)
Ferric sulphide (Fe 2 S 3 )
Iron-pyrites (FeS 2 )
Total sulphide minerals . .
A picked sample from the drive assayed as follows : —
Silver . . . . 20 oz. 3 dwt. 14 gr. Value, £2 lis. per ton.
Copper . . . . 342 per cent.
Molybdenum . . 3-72 per cent., equivalent to 6-2 per cent, molybdenite.
At the mouth of a small left-hand tributary, about a chain above the drive, numerous
ramifying stringers and lenses of quartz, generally about an inch but in one instance up to
3 ft. 6 in. in thickness, carry a little pyrite, chalcopyrite, and molybdenite. A general sample
gave on assay the following results : Gold, 8 gr. per ton ; silver, 17 dwt. 22 gr. per ton ;
copper, 1-01 per cent ; and molybdenum, 0-34 per cent. Higher up this branch, at an eleva-
tion of 60 ft. above the drive, a 10 ft. formation, similar to that exposed in the drive, outcrops.
Here a few irregular " blows " and veins of quartz, the largest 22 in. in width, carry iron,
copper, and molybdenum sulphides in irregular bunches. A picked sample selected from
the largest vein showed the following metalliferous contents : Gold, 6 gr. per ton ; silver,
1 oz. 10 dwt. 21 gr. per ton ; copper, 3-19 per cent. ; and molybdenum, 0-12 per cent. These
values, however, are not continuous throughout the whole vein.
In Silver Creek, about 3 chains above the drive, two veins, 2 ft. and 20 in. in width respec-
tively, carry less than 0-05 per cent, of copper, with traces of gold and silver. Still higher up
the stream the granite occasionally shows small specks of chalcopyrite.
New Anaconda Reef. — The New Anaconda Reef outcrops in the headwaters of Specimen
Creek, at a distance of three-quarters of a mile above its junction with the Little Wanganui
River, and at an altitude of about 1,850 ft. above sea-level. It is a well-defined vein, dis-
tinctly traceable in a north-north-west direction for 12£ chains, while large well-mineralised
floaters indicate a probable further continuance in this direction. About 5 chains above the
main outcrop of the vein some small irregular " blows " and stringers of quartz were observed
in the stream-bed. These carry a little chalcopyrite and melaconite, and probably indicate
a southerly extension of the vein, elsewhere obscured by debris from the steep mountain-slopes.
A general sample from this outcrop showed the presence of 0-59 per cent, of copper, with
3 dwt. 3 gr. of silver per ton.
The New Anaconda Reef itself appears in the bed of Specimen Creek, and extends as a
wall for 160 ft. along the right bank of the stream. A little surface-prospecting has been
undertaken, and this shows a well-defined vein 19 ft. in maximum width, striking about 165°
(true), with apparently a steep easterly dip. It has a definite and strong foot-wall, but the
hanging-wall is not so distinct, the vein breaking up into numerous veinlets and stringers, of
which the full extent has not been ascertained. In consequence, no determination of the
entire width of the vein-formation can yet be arrived at.
A microscopic examination of the enclosing rock shows it to be a partly recrystallized
and highly silicified biotite-granite.
The vein, probably originally of pegmatitic origin, consists of quartz with a certain
amount of feldspar and areas of highly silicified country, the whole displaying a tendency
towards the greisen type. Jointing and Assuring along planes parallel with the vein-wall are
very pronounced. The metalliferous constituents of the ore are similar to those of the Mount
Radiant Reef, but molybdenite is much less in evidence, copper minerals being generally pre-
dominant. The ore-values are for the most part confined to well-defined shoots, in which
the metalliferous constituents often appear in patches and stringers, sometimes up to three-
■ quarters of an inch in thickness. The most extensive ore-shoot has a width of from 3 ft.
to over 6ft., and appears at the south end of the outcrop near the foot-wall. It shows as
a well-defined band parallel with the wall of the vein. A similar but transverse shoot,
18 in. in width, appears 30 ft. from the south end of the outcrop. Beyond the limits of
these shoots the ore is often quite barren, while, again, bunches of chalcopyrite or molyb-
denite may occur irregularly throughout the gangue.
The following assay-results were obtained from samples selected from the New Anaconda
(1.) Southern end of reef above creek . .
(2.) Ore-shoot in creek-bed, south end of
g r -
(3.) Ore-shoot in creek-bed, south end of
(4.) Ore-shoot in creek-bed, south end of
(5.) Ore-shoot in creek-bed, south end of
(6.) Cross-shoot near middle of exposure
(7.) Across face, main exposure
(8.) Across face, main exposure
(9.) Along face, main exposure
(10.) Along face, below sample 9
(11.) Northern end of main exposure
More detailed analyses of Nos. (3), (6), and (7) showed the following percentages of iron
and sulphur : —
(3) . . . . . . . . . . . . 5-75 2-43
(6) . . . . . . . . . . . . 4-90 1-51
Complete analyses of Nos. (4) and (9) are as follows : —
Silica (Si0 2 )..
Alumina (A1 2 3 )
Ferric oxide (Fe 2 3 )
Lime (CaO) . .
Alkalis (K 2 0, Na 2 0)
Cuprous sulphide (Cu 2 S)
Molybdenite (MoS 2 ) . .
Ferric sulphide (Fe 2 S 3 )
Copper Creek Reef. — In the right-hand branch of Copper Creek, at an elevation of 2,000 ft.
above sea-level, a vein is exposed in the creek-bed for 500 ft. in horizontal and 280 ft.
in vertical extension. It has a north-north-east strike, and dips steeply to the west-north-west.
At its lower end it has a width of 2 ft., but thins out and breaks up above into mere stringers.
In places several stringers and veinlets parallel with the main vein were observed, thus bringing
the maximum width of the vein-formation up to 20 ft. Occasional bunches of sulphides,
mostly pyrite and chalcopyrite, occur, together with a little bornite, cuprite, and melaconite,
but the vein-material is generally barren.
Samples selected from various parts of the vein assayed as follows : —
(1.) Lower end of exposure
(2.) Half-way up exposure
(3.) Top of exposure
(4.) From 12 in. to 18 in. parallel vein
For a distance of about 4 chains below the junction of the two branches of Copper Creek
various veinlets are seen to cross the stream-bed. Four of these are each at least 1 ft. in
width, and all are more or less mineralised with pyrite and chalcopyrite. They all have a
strike and dip coincident with that of the main vein, of which they probably indicate the
northerly continuation. In the vicinity and on the track below are numerous large loose
boulders of quartz, which frequently cany considerable amounts of pyrite and chalcopyrite.
These floaters have evidently been detached from a vein having a width of from 2 ft. to 3 ft.,
and apparently have not travelled far. They probably represent wider portions of the present
veinlets now denuded away. The following are the results of various assays : —
Gold per Ton.
From 12 in. to 15 in. veinlet near top Gr -
of second waterfall . . . . 2
Silver per Ton.
Silver per Ton.
From floater below second waterfall
From floater on track near Copper
On the ridge less than a quarter of a mile to the north of the Copper Creek Reef a large
vein outcrops at an elevation of 2,175 ft. Its strike appears to be about north-and-south,
its width indefinite, but probably exceeding 25 ft. It is apparently of pegmatitic origin,
* Not determined.
and presents a series of parallel quartz stringers, with feldspar associated. It is quite barren,
with the exception of two veinlets 6 in. and 12 in. in width respectively, which are highly-
impregnated with pyrite, chalcopyrite, and its decomposition-product — -melaconite.
A sample from the 6 in. vein assayed as follows : Gold, 1 dwt. 6 gr. per ton ; silver,
1 oz. 19 dwt. 1 gr. per ton ; and copper, 4-72 per cent.
Scheelite is said to have been found in the vicinity of this vein.
Fragments of quartz carrying traces of iron and copper sulphides appear on the ridge-
top 5 chains to the west of this vein, while in the creek on the other side of the spur two veins,
2 ft. and 6 in. in width respectively, carry traces of copper minerals. On the spur, at an
elevation of 1,530 ft., a veinlet 6 in. in average width contains traces of copper, whilst the
country in the vicinity shows incrustations of chrysocolla.
Mount Scarlett Reef. — On the southern slopes of Mount Scarlett Range, at a point about
50 chains east of the Mount Scarlett Trigonometrical Station, and at an altitude of 3,700 ft.,
there occurs a vein-formation having a maximum width of about 30 ft. The formation
consists of a series of parallel veins and stringers, varying in width from 8 ft. to a fraction of
an inch, and appears to have a north-easterly strike. Very little prospecting-work has been
done, the formation being merely exposed on the surface in four places in a distance of 3 chains
along its strike.
The enclosing rock is a highly chloritised and silicified biotite-granite, and, like that
of the Mount Radiant Reef, frequently carries values. The vein-quartz is commonly very
rusty, and carries magnetite and sulphides of iron, copper, and molybdenum, with their
oxidation-products, in small branches and stringers.
Samples selected from the three main exposures gave the following assay-results : —
(1.) Northerly outcrop
(2.) Middle outcrop
(3.) Southerly outcrop
About 20 chains north of Mount Scarlett Trigonometrical Station a formation from 6 ft.
to 8 ft. in width shows several stringers and veinlets, the largest of which is 10 in. wide, and
strikes 116° (true), with north-easterly dip of about 30°. The enclosing country is chloritised
porphyritic biotite-granite. The quartz is sometimes rusty, and shows a little pyrite and
chalcopyrite in finely disseminated grains. A general sample gave on assay : Gold, 3 gr. per
ton ; silver, 1 oz. 1 gr. per ton ; copper, 0-14 per cent.
Mackay's Reef. — A well-defined vein, known as Mackay's Reef, outcrops on the crest and
western slopes of the Mount Gorgeous Range, at a point about three-quarters of a mile north-
west of Mount Gorgeous, and at an elevation of 3,685 ft. above sea-level. On the top of the
ridge the vein is exposed for a distance of about 10 ft., and has a width varying from 9 in. to
18 in., with a strike of 64° (true) and a dip of 28° to the south-eastward. About 75 ft. lower
down the western slope the vein is again seen for a distance of about 30 ft. It is here from
3 ft. to 7 ft. in width, and both walls are well defined and persistent. The enclosing rock is a
gneissoid biotite-granite, which has been crushed, partly recrystallized, and silicified. The
vein-quartz is milky-white, but stained along fracture-planes by iron-oxides. As a rule the
quartz is barren, but in places it shows highly pyritic bands up to three-quarters of an inch
in width, carrying a little chalcopyrite. Again, occasional bunches about 3 in. in diameter
and small patches of finely crystalline pyrite and galena, with a little blende, occur. Large
bunches of galena and blende are said to have been obtained from this vein.
A general sample, excluding occasional nodules of sulphides, selected from the outcrops
assayed as follows : Gold, 1 gr. per ton ; silver, 2 dwt. 11 gr. per ton ; copper, 0-08 per cent. ;
zinc, 0-04 per cent. ; and lead, a trace.
Silver per Ton.
Crabbe's Reef. — On the northern slopes of a lateral spur from Mount Eadiant, 25 chains
south-east of the Mount Radiant Eeef, and at an elevation of 3,230 ft., is a 10 ft. vein-forma-
tion exposed along its strike for 28 ft. The formation shows many points of similarity to
that of the Mount Radiant Reef — the stockwork nature being evident, and both vein-material
and country carrying more or less mineral. The enclosing rock is a silicified muscovite-gneiss.
Molybdenite is very general throughout the vein-material, and associated with it is some
chalcopyrite. As a rule, the bulk of the latter mineral is finely disseminated throughout the
gangue, though occasionally it occurs in streaks and bunches. Melaconite is common in
granular form, and crystals are occasionally seen, while stains of cuprite sometimes appear.
A sample of ore gave on assay the following results : Gold, 1 gr. per ton ; silver, 1 dwt. 5 gr.
per ton ; copper, 0-92 per cent. ; molybdenum, 0-23 per cent.
Swag Saddle. — A well-defined pegmatitic vein, with a maximum width of about 30 ft.,
appears at an altitude of 3,635 ft. on Swag Saddle, a quarter of a mile to the north-west of
the Mount Radiant Reef. It has a north-westerly strike, with steep dip to the north-east.
The Vein-material is a bluish quartz, sometimes rather flinty, and generally quite barren.
Metalliferous contents are practically confined to a streak, 4 in. to 6 in. in width, running
parallel with the strike of the vein near the foot-wall. Chalcopyrite is present, generally
finely crystalline, with pyrite and a little molybdenite and molybdite. A sample from this
streak assayed : Copper, 0-51 per cent. ; molybdenum* 0-33 per cent.
Piano Creek. — On the open country at the head of Piano Creek, and 16 chains north-west
from the last outcrop, at an elevation of 3,500 ft., a small outcrop, 3 ft. by 3 ft. 6 in., of
cupriferous, rather flinty, vitreous quartz has been exposed. The enclosing rock is a gneissoid
biotite-granite, somewhat chloritised. Finely crystalline chalcopyrite, with sometimes a
little molybdenite, appears either in small bunches or more commonly fills innumerable fracture
spaces in the gangue. A general sample from this outcrop assayed as follows : Gold, 1 gr.
per ton ; silver, 3 dwt. 2 gr. per ton ; copper, 0-53 per cent. ; molybdenum, 0-09 per cent.
Silver Greek. — Another vein is exposed in the head of Silver Creek, about 20 chains east of
the Mount Radiant Trigonometrical Station, and at an elevation of 3,500 ft. This vein has
a width of about 15 ft., with a well-defined foot-wall. It has a steep northerly dip, and is
exposed along its west-north-westerly strike for 120 ft. The vein-material is a bluish quartz,
frequently somewhat flinty and occasionally rusty. Metalliferous contents are restricted
mainly to a band about 1 ft. wide near the foot-wall, but are occasionally seen throughout
the bulk of the vein-stuff. Finely crystalline pyrite and chalcopyrite are most conspicuous,
while melaconite, chalcocite, molybdenite, and molybdite are occasionally present. The
following are the results of samples selected from the vein : —
Gold per Ton. Silver per Ton. Copper. Molybdenum.
Gr. Dwt. gr. Per Cent. Per Cent.
(1.) General sample . . 1 1 20 0-34 0-006
(2.) Sample from 1 ft. mine-
ralised band . . 1 8 4 0-78 0-03
Fugel Creek. — Just at the mouth of Fugel Creek, at an elevation of 2,150 ft. above sea-
level, a veinlet varying in width from 6 in. to 9 in. crosses the stream-bed. It has a north-
easterly strike, with a dip of 40° to the south-east, and is exposed for a distance of 15 ft., its
northern extremity butting against a joint plane in the granite, which appears to cut it out.
The veinlet is highly impregnated with pyrite, with minor quantities of chalcopyrite, molyb-
denite, and their oxidation-products. It is apparently of pegmatitic origin, molybdenite
largely replacing the muscovite, of which occasional flakes still remain. A general sample
gave on assay: Gold, 7 gr. per ton ; silver, 23 gr. per ton ; copper, 0-08 per cent. ; molybdenum,
0-11 per cent. ; iron, 5-04 per cent. ; sulphur, 2-74 per cent.
Johnson River. — In Johnson River, about 7 chains above the mouth of Fugel Creek, at
an elevation of 2,250 ft., indications of copper and molybdenum were found in a vein- forma-
tion which possibly represents a northerly continuation of the veinlet in Fugel Creek. The
formation has a width of 5 ft. 3 in., and shows several 1 in. to 2 in. parallel stringers crossing
the river-bed with a north-easterly strike and steep south-easterly dip. The stringers are of
pegmatitic origin, showing quartz, pinkish feldspar, and a little mica, and follow generally
the master joints of the enclosing biotite-muscovite-granite. Several of the stringers carry
small bunches of pyrite and chalcopyrite, with traces of molybdenite. Lower down the river
similar stringers are occasionally encountered, until the mouth of Fugel Creek is reached.
A general sample from the vein-formation gave : Gold, 4 gr. per ton ; silver, 6 dwt. 3 gr.
per ton ; copper, 0-11 per cent. ; molybdenum, 0-05 per cent.
Gold Creek. — Near the head of Gold Creek, a left-hand branch of Fugel Creek, at an eleva-
tion of 3,560 ft., a vein having a width of 2 ft. 3 in. is exposed along its strike for 16 ft. It
strikes 76° (true), and dips steeply to the west of north. The quartzose gangue is of a flinty
appearance, frequently stained with iron-oxides, and carries a very little chalcopyrite and
pyrite, both finely disseminated, and in occasional small nests and bunches up to an inch
in thickness. Traces of molybdenite were also observed.
Lower down, at an elevation of 2,530 ft., a vertical quartz vein 18 in. wide, striking 26°
(true), outcrops in the stream-bed. Pyrite, chalcopyrite, and a little molybdenite are present,
generally filling fracture spaces in the quartz. A little melaconite and bornite were also observed.
Midway between these two outcrops a vein-formation 2 ft. in width, frequently very
rusty, shows occasional malachite stains.
A sample from the lowest outcrop in Gold Creek showed the following metalliferous con-
tents : Gold, 2 gr. per ton ; silver, 4 dwt. 23 gr. per ton ; copper, 0-38 per cent. ; molybdenum,
0-025 per cent. ; iron, 3-31 per cent.
Blacktopp Creek. — Near the head of Blacktopp Creek, on the western slopes of Mount
Radiant Range, to the west of Mount Anaconda, at an elevation of 2,850 ft., a vein-formation
12 ft. in width is exposed. The formation shows three lenses of pegmatitic quartz, with
some feldspar, having a maximum width of 2 ft. 3 in., 15 in., and 15 in. respectively, but
rapidly thinning out in all directions. The enclosing country is pink porphyritic biotite-
granite. The formation as a whole shows a general north-westerly strike with steep north-
easterly dip. The middle lens appears to be quite barren, but the outer ones, particularly
the more easterly, frequently show pyrite, chalcopyrite, and melaconite, with a little molyb-
denite and stains of malachite. The following results were obtained from samples selected
from the outer lenses : —
Gold per Ton.
(1.) From eastern lens . . 2
(2.) From western lens . . 2
Minor Occurrences. — -In Smith Creek, about 15 chains above its mouth, a quartz vein
having an average width of about 18 in., with north-easterly strike and steep north-westerly
dip, carries a little pyrite, with some chalcopyrite. A general sample assayed : Gold, 2 gr.
per ton ; silver, 3 dwt. 16 gr. per ton ; copper, 0-16 per cent.
A 2 ft. vein that appears in McHarrie Creek, about 30 chains above its mouth, and at
an altitude of 1,650 ft. above sea-level, has a north-east strike with steep dip to the north-
west, and is exposed along its strike for a distance of 12 ft. The vein consists of extremely
laminated quartz, with rusty bands and bunches of pyrite and a little chalcopyrite. The
following results were obtained from assays of samples from this vein : —
Silver per Ton.
Gold per Ton.
Silver per Ton.
(1.) Lower part of vein
(2.) Upper part of vein
A 1 in. stringer, carrying a little chalcopyrite, bornite, and malachite, appears in the
bed of the Little Wanganui River near the upper foot-bridge, at an altitude of 890 ft.
A creeklet entering the river close by on the left* side shows a 2 ft. vein with well-defined
walls, having a north-easterly strike and westerly dip of 54°. The quartz is frequently rusty,
with bunches of pyrite and a little chalcopyrite and molybdenite. A general sample showed
a trace of copper.
In a lower left-hand creeklet a well-defined vein, varying in width from 1 ft. to 4 ft., has
an east-and-west strike with steep northerly dip. The quartz is sometimes laminated, and
is much like that of the last-mentioned vein. A sample on assay showed the presence of
0-13 per cent, of copper.
Near the mouth of a small right* branch of the Little Wanganui, 10 chains below Smith
Creek, a vein-formation 6 ft. in width outcrops. At this spot there appear several lenses
of quartz, the largest 4 ft. in maximum width, with numerous reticulating stringers, the whoh
forming a stockwork evidently of pegmatitic origin. The formation strikes 61° (true), with
steep southerly dip. About 10 chains to the north-west it outcrops again on the hillside at a
point some 230 ft. above the first outcrop, but is here only 18 in. wide. In both outcrops
the quartz is sometimes rusty, with small bunches of pyrite and a little chalcopyrite. Assays
of samples showed traces of copper, gold, and silver.
On the ridge between McHarrie and Tangent creeks, at an altitude of 2,930 ft., there is
exposed a 2 ft. vein-formation containing a 3 in. band that carries finely crystalline pyrite
and marcasite, with a little blende, and a trace of molybdenite.
A little chalcopyrite and molybdenite appear in a 1 ft. vein near the head of Drain Creek,
at an altitude of 2,228 ft. The vein strikes about east-and-west, with a dip of about 30° N. A
general sample assayed : Silver, 3 dwt. 18 gr. per ton ; copper, 0-34 per cent. ; molybdenum,
0-08 per cent. A large floater in Lawrence Stream may have had its origin in this vein. In
this boulder, pyrite, chalcopyrite, cuprite, chalcocite, melaconite, and a little galena were
observed. A general sample assayed : Gold, 15 gr. per ton ; silver, 5 oz. 11 dwt. 14 gr. per
ton ; copper, 0-49 per cent.
Near the northern end of Mount Herbert Range, at an altitude of about 3,800 ft., three
rusty veins outcrop. They each have a maximum width of about 2 ft. 6 in., but rapidly
pass into the enclosing rock — a silicified gneissoid biotite-granite. They contain frequent
bunches, about an inch in diameter, of coarsely crystalline pyrite, which have sometimes
weathered out, giving the quartz a honeycombed appearance. Assays of samples showed
entire absence of the precious metals.
Near the head of Reef Creek — a right-hand branch of Granite Creek — at an altitude of
1,285 ft., a band of silicified grauwacke, having a maximum width of about 50 ft., has some-
what the appearance of an immense reef. Silicification has probably accompanied the in-
trusion of two small granitic sills, 3 in. and 5 in. in width respectively. The rock is finely
pyritised, and occasionally assumes a slightly bluish colour, owing to finely disseminated
molybdenite. A sample on assay was found to contain 0-03 per cent, of molybdenum, but no
gold or silver.
During the course of the survey, floaters of metalliferous quartz were occasionally observed
in positions which precluded their having originated from any of the known veins. Of these
may be mentioned an occurrence near the " pakihi " on Lawrence Saddle, in the headwaters
of a small branch of Huia Creek. Here several large blocks of quartz, one 4 ft. in length and
2 ft. 6 in. in width, carry bunches and veinlets of finely crystalline pyrite with chalcopyrite
and traces of galena. A sample from the large block assayed as follows : Gold, 1 dwt. 6 gr. per
* In this bulletin " right " and " left," in connection with stream- tributaries. &c, aro used in the geo-
graphical sense — that is, one is supposed to be looking down the main stream.
3— Mt. Radiant.
ton ; silver, 29 oz. 7 dwt. 6 gr. per ton ; copper, 0-53 per cent. This quartz probably bad
its origin in the denuded soutb end of Mount Stormy Range, near Black Rat.
A small floater found near the head of a right-hand branch of Kakapo River showed a
3 in. veinlet of pyrite, carrying 5 gr. of gold and 1 oz. 5 dwt. of silver to the ton.
A boulder of quartz carrying a considerable amount of bornite was noted in the Little
Wanganui River, midway between Copper Creek and Piano Creek, and points to the possibility
of further outcrops of cupriferous quartz on the ridge between these two streams.
A small boulder of quartz picked up in Allen River, about a mile and three-quarters above
its mouth, showed a considerable amount of pyrite and chalcopyrite. An assay gave the
following results : Silver, 3 oz. 10 dwt. 13 gr. per ton ; copper, 5-14 per cent. ; molybdenum,
0-04 per cent.
General Observations on Metalliferous Veins.
Prospecting operations on the Mount Radiant Copper-field have been carried out in a
very haphazard fashion. With the exception of a small cross-cut on the Mount Radiant Reef,
and a little surface-work on that vein and the New Anaconda, practically nothing has been
done beyond the location of numerous cupriferous veins. Even the simple method of proving
the continuity of a vein or vein-formation by systematic trenching along the strike has not
been resorted to, and in consequence the field presents nothing more than a mere prospecting
It is highly probable that a connection exists between the Mount Radiant Reef, the out-
crop on Swag Saddle, and that at the head of Piano Creek. Should prospecting operations
show this to be the case, the vein-formation will be proved to have a length of at least half
a mile. Similarly, a further extension of 25 chains to the south-east would be proved if con-
nection with Crabbe's Reef could be established. It is quite within the bounds of possibility
that the New Anaconda Reef may prove to be a further continuation at a lower level of the
same vein-formation, which would then have a strike - extension of over two miles. The
occurrence of cupriferous quartz in Blacktopp Creek may be an intermediate outcrop between
those of the New Anaconda and Piano Creek, but, apart from this, no other connecting outcrop
has been observed.
On the northern side of the Little Wanganui River, a connection may be ascertained
between the Mount Scarlett Reef and the outcrop in McHarrie Creek, while the copper indica-
tions in the river-bed near the upper foot-bridge and the vein in the creeklet a little to the
south-west may be a further continuation of the same formation.
A consideration of the result of assays of samples selected from the various outcrops shows
that the ore is in general exceedingly low grade, the copper-contents as a rule falling far below
the limit at which an ore could be successfully treated. The general low percentages of gold,
silver, and molybdenum are also extremely discouraging. A few remarks upon the various
metalliferous contents of the ore may be of interest.
Copper. — The main copper mineral present in the ore is chalcopyrite, which for many years
has been the main source of the world's supply of copper. Assays show that in general the
amount of copper present in the ore is considerably under 1 per cent., but rises sometimes in the
Mount Radiant Reef to over 1 per cent., and in the main shoot of the New Anaconda Reef
to nearly 2-5 per cent.
Molybdenum. — Although classed as one of the " rare metals," molybdenum is by no
means as uncommon as this term would suggest, the sulphide molybdenite being of frequent
occurrence in metalliferous veins, especially in North America and Australia. The metal
is largely used for hardening and toughening steel, and, as a means of imparting these qualities,
is said to be preferable to tungsten. In combination with other elements it is also useful as
a dye, as a means of imparting a blue glaze to chinaware, and in one or two chemical processes.
Molybdenite is occasionally used as a lubricator for heavy machinery.
The value of molybdenum fluctuates considerably, but may be taken at Is. 3d. per pound,
equal to £125 per short ton (2,0001b.).* The production of the metal in the United States
was, in 1900, 32,0001b., with 11,0001b. of ferro-molybdenum.f Owing to the increasing
demand for special steels the market for molybdenum is steadily widening. It is highly
probable, however, that supply and demand are under the control of a few persons or corpora-
tions, and the production of large quantities of the metal would have the effect of glutting
the market, and so reducing the market price. jjftj
Assays of samples from the various vein-outcrops of the subdivision show that molyb-
denite is almost invariably present, though usually in amount less than 0-1 per cent. Occa-
sionally, however, the amount is considerably in excess of this, the highest recorded being
4-06 per cent, of molybdenum — equivalent to 6-76 per cent, of molybdenite. This was obtained
in one sample from the main ore-shoot of the New Anaconda Reef, but cannot be considered
as representative of the whole ore-shoot. Molybdenite is, on the whole, more prominent as
a metalliferous constituent in the Mount Radiant Reef than in the New Anaconda.
Gold and Silver. — Upon the value of gold and silver, almost invariably present in copper-ores,
frequently depends the commercial success of a low-grade copper venture. In the Mount
Radiant ores, so far as they have been exposed, values in gold and silver are very low, the
average of all the samples from the main shoots of the New Anaconda Reef showing only 1-2 gr.
of gold and 18 dwt. 6 gr. of silver to the ton. The amounts of gold and silver, except in occa-
sional instances, do not appear to be dependent upon the proportions of copper and molyb-
denum present, though no doubt they are to some extent associated with these metals. Assays,
again, entirely fail to show any definite ratio between the amounts of gold and silver in the
ore. It is possible that the precious metals are, in the main, associated with the pyrite present
in the ore, though this is not borne out by those analyses in which the iron-sulphide has been
determined. It is noticeably the case that when galena occurs in the ore, values in silver
and gold are relatively high.
Sulphur. — Sulphur occurring in combination with iron or other metals is, when present in
sufficient quantity, of value as a fuel in the " pyritic smelting " process. In these ores the
proportion of sulphides is much too low to admit of the adoption of this process, the' highest
percentages noted being from the veinlet at the mouth of Fugel Creek, which carries 5-04
per cent, of iron and 2-74 per cent, of sulphur ; and from samples Nos. 3 and 7 of the New
Anaconda Reef (quoted on page 28), which show 5-75 per cent, and 7-84 per cent, of iron,
2-43 per cent, and 4-43 per cent, of sulphur, respectively. In each case part of the iron is in the
form of oxide ; and probably none of the samples collected contains more than 10 per cent.
of sulphides available as fuel, whereas in pyritic smelting at least 80 per cent, of sulphides
is required for the successful operation of the process.
Lead and Zinc. — Analyses have failed to show more than traces of lead and zinc in any
instance, and, with the exception of Mackay's Reef, in which occasional bunches of galena
and zincblende were observed, the occurrences of these metals within the subdivision can
scarcely be considered of economic importance.
General Conclusions. — From the above remarks it will be seen that the Mount Radiant
Copper-field is essentially a low-grade copper proposition still in the stage of a prospecting
The outcrop which has afforded the most promising results is that of the New Anaconda
Reef, the main ore-shoot of which carries an average of nearly 2-5 per cent, of copper. The
Mount Radiant Reef, carrying in one of its numerous veins a copper-content of 1-2 per cent.
with 1-76 per cent, of molybdenum, is next in importance. These percentages might be
*At present (July, 1910) molybdenite (the sulphide) in quoted at Is. per pound, so that the metal
should be not worth less than Is. 8d. per pound, or about £1<>7 per short ton as occurring in the ore.
t J. Ohly, " Analysis, Detection, and Commercial Value of the Rare Metals," p. .'i!».
brought up to a commercial standard by judicious hand-sorting. In this connection it should
be noted that the low-grade copper-deposits of Ely, Nevada, which carry considerably less
than 3 per cent, of copper, with traces of gold and silver, are made to pay by being worked
on a tremendous scale, the concentrating-plant being capable of treating 5,000 tons of ore
per diem.* In the case of the Mount Radiant district it must be noted that the copper-
deposits are in a remote mountainous part of New Zealand, and therefore the cost of opening
up the mines and establishing treatment-works for the ore would be very great.
It has been shown that the pyritic contents of the ore are not present in sufficient quantity
to admit of the treatment by the " pyritic smelting " process, and a system of concentration
followed by blast-furnace smelting, such as obtains at Ely, Nevada, would be the best means
of treatment. Should it be found advisable to save the molybdenite, this could be done by
fine grinding and a final concentration with oil (Elmore process).
Suggested Prospecting Operations. — The New Anaconda Reef, from assay-results and
from the fact that it has all the appearance of a strong vein likely to be continuous both in
vertical and in horizontal extension, as well as from its relative accessibility, presents the
most promising prospecting proposition of the field. In order thoroughly to prospect this
vein, its horizontal extension should be proved by systematic trenching along its strike, both
in a northerly and in a southerly direction. Its continuation in depth should then be ascer-
tained by a cross-cut drive at a considerable depth below the present outcrop of the vein.
Special facilities in this connection are afforded by Specimen Creek, which follows a course
roughly parallel with the vein near its western side for a distance of about 10 chains, readily
offering from 100 ft. to 200 ft. of " backs," while its close proximity to the vein would obviate
the necessity of much " dead work " before the vein was reached. Good mining-timber
is plentiful in the neighbourhood, and water-power is readily available. Careful sampling
should be undertaken, both upon the surface outcrops exposed and throughout the drive,
when a fair conclusion as to whether further prospecting was warranted or not would be
In the case of the Mount Radiant Reef, assay-results are less encouraging than at the
New Anaconda Reef, and prospecting operations would be more difficult. The irregular
veins presented in the formation are not of sufficient size, nor do the metalliferous contents
seem high enough to warrant its being worked on a commercial scale. It is possible that in
depth the veinlets may unite to form a strong and continuous ore-body, but sinking-operations
to prove this would be expensive. As already suggested, surface-trenching to ascertain the
continuance of the formation and its connection with other outcrops, and with it careful
sampling of the vein-stuff exposed, should be undertaken.
The occurrence in Copper Creek of well-mineralised floaters, which have probably been
derived from a northerly extension of the large reef in this creek, leads to the opinion that
prospecting operations are warranted, more particularly about the western slopes below
the junction of the two main branches.
Little difficulty would be experienced in conducting surface-prospecting operations upon
the Mount Scarlett Reef, since the outcrop occurs in open grassed country, and the work
would necessitate the removal of surface matter only a few inches in depth. The assay-
results from this vein-formation are not, however, very encouraging.
The" well-defined vein known as Mackay's Reef, occurring on the slopes of Mount Gorgeous
Range, is worthy of further prospecting. The vein displays strong walls, and in all probability
is continuous for some considerable distance. Although the results of samples taken by the
Geological Survey are disappointing, future prospecting operations may reveal the presence
of workable deposits of chalcopyrite, galena, and blende.
* Engineering nnd Mining Journal, vol. 83, 1907, p. 509. Later information gives the amount of
copper-ore developed at Ely as 20,000,000 tons, with an average copper- content of 1*9 per cent. See
Mining and Scientific Press, 2nd January, 1909, p. 58.
Auriferous Alluvial Deposits.
Auriferous placer deposits have been found in several parts of the subdivision, and, while in
the majority of cases the deposits have been quite worked out and abandoned, in some spots
work is still carried on in a desultory fashion. Again, in other cases the auriferous contents
do not offer sufficient inducement to the gold-seeker.
Of those places where gold has been found, but which have since been abandoned, Glasseye
Creek ranks first in importance. Mullocky Creek and Kimberley Creek, branches of Granite
Creek, have also yielded gold in the past.
A little gold is still being obtained on the bank of the Little Wanganui River just above
the mouth of Glasseye Creek, while along the beach north of the river " beach-combing " is
sometimes resorted to after heavy weather, to extract the precious metal from the leads of
" black sand " with which it is associated.
Other occurrences of alluvial gold which have been overlooked by or are not sufficiently
tempting to the gold-seeker are found in some small branches of Granite Creek and in Tony,
Blackwater, and Ponga creeks.
Very fine " colours " of gold were obtained in Johnson and Mokihinui rivers, but no
deposits of possible economic importance were noted.
The gold won from Glasseye Creek was for the most part of a coarse " reefy " nature,
the particles generally varying in weight from \ gr. to 5 dwt. It was obtained for the most
part from crevices in the stream-bed, but a considerable quantity was also got from the
alluvium forming the small flood-plains of the stream about a mile below the New Inland
Road crossing. Throughout its course within the subdivision Glasseye Creek flows through
highly argillaceous limestones and feldspathic sandstones of the Kongahu Series, but a little
south of the subdivision the Aorere sediments are encountered. Quartz veins are known
to exist in these, but so far none carrying gold in payable quantities has been found.
The fact that the bulk of the gold from Glasseye Creek was obtained below the New
Inland Road, combined with the fact that little or no fine gold is to be found in the stream-
bed, points to the probabihty that free gold is no longer being shed into the stream. It is
possible that one or more of the known quartz veins at one time carried " specimen " gold,
and that these bonanza portions have long since been eroded away.
The gold in Glasseye Creek is of very high quality, being valued at £4 4s. per ounce.
In Kimberley Creek the gold was derived from a small branch creek draining the terrace
in the vicinity of Trigonometrical Station A C. The gold was much finer than that of Glasseye
Creek, the largest piece found weighing 5 dwt., and was very similar to that found in the
Karamea River, the two being of the same value — namely, £3 16s. to £3 18s. per ounce. The
wash from which the gold was concentrated by the streamlet is still preserved in occasional
patches on the crest of the terrace, and consists of pebbles and cobbles, averaging 6 in. in
diameter, of granite, argillite, and grauwacke, the latter rock frequently reticulated with
fine quartz stringers. It was evidently deposited by the Karamea River in Late Tertiary
or Early Quaternary times.
Certain beds of loosely consolidated conglomerate occurring in the uppermost horizons
of the Kongahu Series outcrop in Granite Creek about two miles and a half above its mouth.
The beds have a north-north-east strike, with westerly dip of about 45°, and are probably
identical with beds outcropping on the Promised Land Road, near the Karamea Bridge, to
the north of the subdivision. The constituent pebbles, which average 1 in. in diameter, are
mainly of a readily decomposed grauwacke, with a good deal of quartz and very minor quantit ies
of granite. Examination of these beds showed that they carry occasional fine " colours "
of gold. It is highly probable that the gold found in Mullocky Creek was a reconcentration
product from these or similar beds, for the old workings showed a wash of similar nature,
but characterized by the presence of pebbles of a rusty-brown quartz. Beds of conglomerate
are said to exist at the head of a branch of Mullocky Creek, and may be auriferous, but these
were not observed during the course of the geological survey.
The gold occurring in Tony, Blackwater, and Ponga creeks, and in some small left branches
of Granite Creek above Egan Creek, probably had a similar origin. The streams generally
run at grade, and prospecting is rendered difficult by the;heavy surface-silt that has to be
stripped away. It is extremely probable that systematic prospecting in these streams will
prove the existence of further small patches of payable alluvial drift.
1 Occasional fine " colours " occur in the gravels overlying the Tertiary rocks in the vicinity
of the Initial Trigonometrical Station.^jfA short distance to the north of the subdivision a
bore was put down in these beds to a depth of 191 ft., and fine " colours " are said to have
been found throughout the entire depth of the bore.
The gold occurring in association with the " black sand " leads on the Little Wanganui
Beach is probably a mixture of gold derived from Glasseye Creek and from rivers discharging
to the south of the subdivision. The best and heaviest gold is obtained near the mouth of
the Little Wanganui Biver, and is valued at £3 19s. per ounce.
A bed of fluvio-marine wash occurring along the base of the bluff on the south side of
the Little Wanganui River, just above the mouth of Glasseye Creek, is being worked at the
present time for gold. At the time of the writer's visit the workings were obscured by slip
matter. The bed of wash is said to be 4 ft. 6 in. in depth, carrying in places 1 dwt. of gold
to the load, and is said to be continuous along the base of the bluff. The gold is valued at
from £3 17s. 7d. to £3 19s. per ounce, and has evidently been derived largely from Glasseye
The fine gold occurring in the Mokihinui Biver probably had its origin in veins in the
Aorere sediments beyond the subdivision. That in Johnson Biver has doubtless been
liberated through denudation of the copper-molybdenum veins occurring in the basin of
While lime is a prominent constituent of most of the rocks of the Kongahu Series, it is,
as a rule, not present in sufficient quantity to produce a limestone of a grade suitable for com-
mercial purposes. The limestones of the Lower Kongahu Formation are generally exceedingly
arenaceous and gritty, but occasional bands containing a high percentage of calcium-carbonate
A slightly dolomitic semi-crystalline limestone, of which a poor outcrop occurs in Drain
Creek, showed on analysis : —
Calcium-carbonate (CaC0 3 ) . .
Magnesium-carbonate (MgC0 3 )
Iron-oxide and alumina (Fe 2 3
Insoluble residue (Si0 2 , &c.)
Water and organic matter . .
A1 2 3 )
Total carbonic anhydride (CO 2 ) .. .. .. .. 43-10
The outcrop of limestone in the Little Wanganui Biver at the base of Black Bat is well
exposed in the track-cutting on the north bank of the river. On the south side of the river
an outcrop of the same limestone shows the whole to have a thickness of about 100 ft. It
is very flaggy, and generally exceedingly arenaceous and gritty, and is sometimes glauconitic,
the bands varying from high-grade hmestone through calcareous grit to a conglomerate with
calcareous matrix. The following are analyses of various samples selected from a zone of less
arenaceous limestone, about 20 ft. in width, exposed in the track-cutting. Nos. 1 and 2 are
from a 2 ft. 6 in. band, while the others are general samples from the whole zone : —
Carbonate of lime (CaC0 3 ) . .
Iron - oxide and alumina
(Fe 2 3 ; A1 2 3 )
Insoluble residue (Si0 2 , &c.)
Water and organic matter . .
100-00 100-00 100-00 100-00 100-00
A band of somewhat flaggy semi-crystalline limestone having a thickness of about 75 ft.
is exposed in the bed of Kakapo River. It is generally of high quahty, but loose boulders
show that it becomes gritty in places. An analysis of a general sample showed the presence
of 99-08 per cent, of carbonate of lime. A very similar limestone, carrying 98-64 per cent,
of carbonate of lime, occurs near the head of Blacktopp Creek.
In Huia Stream the high-quality limestone exposed has a maximum thickness of 20 ft., and
contains 98-05 per cent, of calcium-carbonate.
Rather indefinite outcrops of limestone in the first and third left branches of Lawrence
Stream, at elevations of about 1,640 ft. above sea-level, showed thicknesses ranging between
10 ft. and 20 ft., the percentages of contained calcium-carbonate being 94-96 and 96-96 respec-
In the lowest left branch of Huia Stream a rather gritty limestone, 20 ft. in thickness, shows
on analysis a content of 91-50 per cent, of calcium-carbonate.
The following are analyses of more or less impure limestones from the same horizon as
those already mentioned, with the exception of Nos. 2, 3, and 5, which occur in the lowest
horizon of the Kongahu Series : —
(1.) Argillaceous arenaceous limestone from Huia Stream.
(2.) Arenaceous limestone from head of Maori Gully.
(3.) Arenaceous limestone from Maori Gully, about two miles below No. 2.
(4.) Limestone from outcrop on New Inland Road.
(5.) Limestone from 15 in. band, Little Wanganui Head.
(6.) Lower half limestone-outcrop, Glasseye Creek.
(7.) Upper half limestone-outcrop, Glasseye Creek.
Silica (Si0 2 )
Alumina, (A1 2 3 )
Iron-oxide (Fe 2 3 ) . .
Magnesia (MgO) . .
Carbon-dioxide (C0 2 )
Alkalis and undetermined
100-00 100-00 100-00 100-00 100-00 10000 10000
A consideration of the various analyses quoted shows that the limestones are sometimes
of sufficiently high grade to be of value as fluxes in metallurgical works, as well as for the
manufacture of agricultural lime and, under certain conditions, cement. As regards fluxing-
material, the limestone occurring in Drain Creek is particularly conveniently situated in the
event of copper reduction-works being opened in the vicinity of Belltown.
The following analyses of calcareous rocks from various horizons of the Lower Kongahu
Formation may here be given. Most of the rocks contain a small proportion of feldspar and
mica grains : —
(1.) Highly calcareous, rather argillaceous, sandstone from Mokihinui River.
(2.) Arenaceous hmestone from New Inland Road.
(3.) Arenaceous limestone from New Inland Road.
(4.) Arenaceous limestone from Falls Creek.
(5.) Arenaceous limestone from beach near south end of Big Hill Track.
Silica (Si0 2 )
. . 3815
Alumina (A1 2 3 )
Iron-oxide (Fe 2 3 ) . .
. . 3-36
Carbonic anhydride (C0 2 )
. . 0-85
Alkahs and undetermined
It has been already mentioned that two small seams of lignite, associated with the loosely
consolidated conglomerate of the uppermost horizon of the Kongahu Series, were noted just
north of the boundary of the subdivision, near the Initial Trigonometrical Station.
Large fragments of lignite doubtfully in situ occurring in a small branch of Granite Creek
just east of the Initial Trigonometrical Station, and in two small creeks flowing into the swamp
near Trig. H, show the continuation of one or both of the seams in these directions. The
average thickness of the seams is about 1 ft., judging by the fragments observed. The lignite
is said to be fairly serviceable for household use, but very dirty and sulphurous. An analysis
of a sample from the creek east of Initial Trigonometrical Station is as follows : —
Fixed carbon .. .. .. .. .. .. 19-17
Volatile hydrocarbons . . . . . . . . . . 41-28
Water . . . . . . . . . . . . . . 15-62
Ash .. .. .. .. .. .. .. 23-93
The analysis shows the sample to be lignite of very inferior quality.
The highly argillaceous limestones, calcareous claystones, and sandstones developed to
such an extent in the lower horizons of the Kongahu Series frequently emit, upon fresh fracture,
a distinct odour of petroleum. Apart from this odour, no other indications of the presence
of petroleum were noted. A distinct oiliness was observable in the water of a small branch
of Glasseye Creek, but this was probably due to the decay of surface vegetable matter.
Owing to the synclinal arrangement of the beds of the Kongahu Series it is not very
probable that accumulations of mineral oil of sufficient extent to be of commercial interest
can occur within the subdivision.* There is a possibility, however, that minor anticlines capable
of acting as oil-reservoirs may exist within or near the area. A marked feature of the oil
present in the rocks is its volatile nature. In several specimens of claystone, smelling strongly
of petroleum when taken in the field, no trace of oil was observable, even by heating in a test-
tube, a few weeks after. In consequence of this, no conclusion could be come to as to the
exact nature of the oil.
Building and Ornamental Stone.
Much of the granite of the subdivision is of high-grade quality, and its natural jointing
should make it readily adaptable for masonry. In many places the pink porphyritic granite
would be eminently suitable for use as an ornamental stone. A particularly fine rock of this
nature occurs near the head of Tangent Creek, but its inaccessibility precludes all possibility
of its ever being worked commercially. The same objection applies to all the granitic rocks
of the subdivision : their remoteness from the coastal margin forms an insuperable bar to
their export on a payable scale.
* That is, if the anticlinal theory of oil-accumulation is approximately correct, as it is generally con-
sidered to be.
Abbot and McHarrie, pioneers . .
Acidic dykes . .
„ distribution of
„ mode of occurrence of
„ petrology of
(See also Aplite, Pegmatite.)
Acidic igneous rocks . .^ m . .
(See also Granite, &c.) ^g.
Acknowledgments . . lf , f . .
Allen Range . .
„ „ loose cupriferous quartz
Analyses of ores 27, 28, 29, 30, 31
Anticlinal oil theory
Aorere Series . .
,, age of
„ distribution of
,, metamorphism of
„ petrology of
,, structure of
Aplite dykes . .
Auriferous alluvial deposits
(See also Gold.)
8, 13, 14, 15
. .. 14-15
in .. 34
, 32, 33, 34, 35
21, 38, 39, 40
8, 9, 12-13
13, 14, 15
8, 12, 13
. . 19, 21
Basic and semi-basic igneous rocks
Basin formed in strata
Beach deposits (see Littoral deposits).
Beaches, gold in
Bell, J. M.
Black sand, auriferous
Blacktopp Creek, veins in
Blackwater Creek, gold in
Blende, zinc . .
Bridle-tracks . .
Buller fault, lower
Butte, cupriferous veins oi
Calcareous bands and concretions
. . 12, 17
. . 4, 37
4, 22, 37, 38
. . 14, 28
. . 14, 26
4, 22, 37, 38
. . 32, 34
. . 37, 38
30, 35, 36
. . 3, 10
6, 26, 33, 34
. . 8, 13
. . 19, 22
>. 5, 6
Cement, limestones for . .
Clarke, E. de C.
Communication, means of
Concentration of ore
Conducting work, plan of
„ gold in . .
Continental land, ancient
Copper, discovery of
„ in ores, remarks on
Copper Creek Reef
Copper-bearing veins (see Cuprifer
Covellite t .-
Cupriferous veins, &c. . .
Dairy-farming . .
Debris, older and newer
. . 6, 24
4, 25 et seq.
25, 26, 30
19, 22, 41
2, 9, 22
. . 19, 21
20, 21, 37, 38
. . 9, 10
. . 12, 13
, 2, 4, 5, 24-36
25, 29, 31
age of . .
„ „ content of . . 22
„ „ distribution of 22
„ „ estuarine deposits of 22
,, „ fluviatile deposits of 22
„ „ lacustrine deposits of 23
,, „ marine deposits of 22
„ ,, swamp deposits of 23
„ ,, talus deposits of . . 23
Denudation . . . . 3, 8, 9, 14, 16, 17, 22
Depression of land . . . . 9, 10, 11, 19
Diabasic rocks. . . . . . . . 13, 16
Diorites . . 14, 15, 16
Drain Creek, limestone in . . . . 40
„ vein near head of . . . . 33
Dykes, acidic . . . . . . 8, 13, 14-15
„ semi-basic . . . . 8, 13, 15-16
Dynamic metamorphism . . . . 13
Earth-lineaments indicating faulting . . 11
Economic geology . . . . . . 24—41
Elevation of land 2, 3, 8, 9, 10, 14, 22
Elmore process . . . . . . 36
Ely, low-grade copper-ore of . . . . 36
Enrichment, secondary . . . . . . 25, 26
Epidote .. .. .. . . 12, 13
Estuarine deposits . . . . . . 22
Fall Creek . . . . . . . . 3
Faulted blocks . . . . 3, 9, 10
Faults, &c. . . . .3, 8, 9, 10, 11, 12, 16, 17
Fault-scarps . . . . 3, 9, 11, 12, 16, 23
Flats, river . . . . . . . . 4
Flax, New Zealand . . . . . . 7, 24
" Floaters," metalliferous 27, 29, 33, 34, 36
Fluviatile deposits . . . . . . 22
Fluvio-marine wash (auriferous) . . . . 38
Folding of strata . . . . 8, 9, 11-12, 17
Foot-tracks . . . . . . . . 5, 6
Fossils . . . . . . 18, 19, 20
Foraminifera of Lower Kongahu Formation 18, 20
Fruit-growing . . . . . . . . 7
Fry, S. . . . . . . . . 7
Fucoid remains . . . . . . 18, 19
Fugel Creek, vein in . . . . . . 31, 35
Galena .. .. . . 30, 33, 35, 36
Geological history . . . . . . 9
Geology .. .. .. .. 8-23
detailed .. .. .. 12-23
,, economic . . . . . . 24-41
,, structural . . . . . . 10-12
Glacial deposits, material resembling . . 19
Glaciation, possibility of . . . . 3
Glasseye Creek, gold in . . . . . . 4, 37
Gneisses and gneissoid rocks . . 14, 30, 31, 33
Gold, alluvial . . . . . . 4, 21, 37-28
„ „ character and value of . . 37, 38
,, in veins, &c.
Gold Creek, veins in
Granite and granitic rocks
4, 25, 27, 30 et seq.
3, 4, 24
3, 10, 11, 17
8, 13-15, 19, 20,
24 et seq., 41
age of . . 9, 13
distribution of . . 14
inclusions of Ao-
rere rocks in . . 12, 13
master- joints of
11, 15, 25
mode of occur-
rence of . . 8, 13
veins in 24 et seq.
4, 37, 38
Graphic intergrowth of quartz and feldspar 14, 15
Grauwackes . . . . . . 8, 12, 13
Greisen-like veins . . . . . . 25, 28
Grits . . . . . . . . 19, 20, 22
Haast, Sir Julius Von . .
Hamilton, A. . .
Hand-sorting of ore
„ „ veins of
(See also Granite, Dykes.)
(See also Mining.)
Intermediate and basic igneous rocks
8, 9, 13-16
4, 6-7, 24
Intermediate and basic igneous rocks, age of
Intermediate and basic igneous rocks, dis-
tribution of . . . . . . . . 15
Intermediate and basic igneous rocks, mode
of occurrence of . . . . . . 15
Intermediate and basic igneous rocks, origin
of .. .. .. .. .. 15
Intermediate and basic igneous rocks, pe-
trology of . . . . . . 16
Introduction . . . . . . . . 1
Intrusions, granitic . . . . 8, 9, 12, 13
Iron- oxide, hydrous . . . . . . 23
„ gold in . ,
„ veins of. .
„ cupriferous " floater " in
Karamea, Township of . .
Kimberley Creek, gold in
Kongahu, settlement of
post-office at. .
Formation, Lower . . 16, 17
„ „ fossils of
Upper . . 16, 17,
,, „ fossils of
Point, fault at
„ granite at
„ age of . .
„ content of
„ distribution of . .
., fossils and palaeontology
of .. .. 9,
„ folding and structure of 11-
„ petrology and special areas
„ thickness of
Land, capabilities of
6, 7, 24
Lands and Survey Department . .
Lawrence Saddle, vein
4, 23, 24
Lead and zinc in ores
Lenticular veins, &c.
27, 32, 33
20, 21, 40
„ analysis of
Lime, limestones for
13, 14, 16
. . 14, 16
„ analyses of
38, 39, 40
„ for fluxing
Little Wanganui, settlen
lent of . .
post-office at . .
Perry, settlement of
,, post-office at
River . .
„ alluvial gold in
. 37, 38
,, flood-plains of
vein " floaters "in
veins in or near
. . 4, 19, 20, 21, 22, 37, 38
McHarrie Creek, veins in or near . . 32, 33
McKay, Alex. . . . . 9 (footnote), 10, 11
Mackay, John . . . . . . . . .1
Mackay's Reef . . . . . . 30, 36
Maclaurin, J. S. . . . . . . 2
Magellania magna, n. sp. . . . . 18
Magmas, granitic . . . . . . 13, 15
„ mixing of . . . . . . 15
Magmatic waters . . . . . . 25
Mail-services . . . . . . . . 6
Maine, molybdenite veins of . . . . 26
Malachite . . . . . . 25, 26, 32, 33
Marine deposits . . . . . . 22
(See also Beaches, Littoral deposits, &c.)
Marshall, P. . . . . . . . . 13
Melaconite .. .. 25,26,27,29,30,31,32
Metalliferous zones and veins 1, 2, 4, 5, 14, 15, 24-36
Metamorphism . . . . 8, 12, 13
Metasomatic replacement . . 13, 25, 26
Meteoric waters . . . . . . 25
Minerals, secondary . . . . . . 25
(See also Veins, &c.)
Mining, history of . . . . 4, 5
Miocene rocks . . . . . . 9, 16-22
(See also Kongahu . Series. )
Mokihinui River . . . . . . 3
gold in.. .. .. 38
Molybdenum, price of . . . . . . 35
„ uses of . . . . 34
Molybdenite . . . . . . 4, 25 et seq.
Molybdite . . . . . . . . 26, 31
Mount Gorgeous Range, cupriferous reef of . . 30, 36
Mount Herbert Range . . . . . . 3, 33
Mount Radiant Block . . . . . . 10, 24
Range . . . . . . 3, 10
Reef . . 4, 26-27, 34, 35, 36
,, Subdivision, position of . . 1
Mount Scarlett Reef . . . . . . 30, 36
Mount Stormy Block . . . . . . 10
„ Range . . . . . . 3, 10
Mountains . . . . . . . . 3
Mullocky Creek, gold in . . . . 4, 37
Muscovite, replacement of, by molybdenite 25, 31
New Anaconda Reef
" New Inland Road "
6, 27-29, 34, 35, 36
. . 5, 6
O'Connor, Mount . . . . . . 3, 10
" Old Inland Road " . . . . 5
" Old land " . . . . . . . . 2, 3
Older and newer debris . . . . . . 22-23
Ordovician rocks . . . . 8, 9, 12-13
(See also Aorere Series.)
Orthoclase, large phenocrysts of . . ..11.15
Oscillations in land-level .. .. 9, 19
(See also Depression, Elevation.)
Parapara Subdivision, Aorere roc
Pegmatite dykes, &c. . .
Pegmatitic veins (metalliferous)
Petroleum, indications of
Petrology of Aorere Series
„ Kongahu Series
„ igneous rocks
Piano Creek, vein at head of
Ponga Creek, gold in
Pyrite in veins, &c.
Pyritic smelting impracticable
25 et seq.
2, 9, 22
4, 5, 25, 26
Quartz in veins, &c
25 et seq.
25 et seq.
cupriferous veins of
4, 26-27, 34, 35, 36
(See also Mount Radiant.)
Recrystallization of rocks
Reef Creek, silicified rock in
Reefs and lodes (see Veins).
Replacement of various kinds
„ direction of, indicating faulting, &c
Roads, bridle-tracks, &c.
" Rocks Road "
13, 14, 28, 30
12, 13, 14, 25, 26,
28, 30, 31, 33
Sandstone, analysis of calcareous argillaceous
Sandstones . . . . 19.
„ „ reef at
Schists |$2 . . . . 8.
„ enrichment . .
Sequence of formations . .
Settlement ^and^history of mining
Shearing of rocks
(See also Faulting.)
Sheen produced by mica
Shelly conglomerate, &e.
Silicification of rocks, &c.
Silver in veins, &c.
Silver Creek,jfdiscovery of copper in . . 4
veins in . . 4, 26-27, 31, 34, 35, 36
(See also Mount Radiant Reef.)
Slickensided coatings of molybdenite
Smith Creek, vein in
Stone, building and ornamental . .
Structure of formations, general . .
Subsidence of land (see Depression).
Sulphur in ores
Swag Saddle, vein at
12, 13, 28, 30, 31, 33
. . 13, 33
4, 25, 27, 30 et seq.
13, 14, 16
9, 12, 13
2, 4, 23
17, 21, 40
Tadmor Track . . . . . . 6
Takaka-Karamea fault . . . . . . 10
Talus deposits . . . . . . 9, 23
Tangent Creek, dykes in . . . . 15
„ ornamental granite of . . 41
„ vein near . . . . 33
Tarns • 4
Tertiary rocks! '. '..2,9, 10, 11-12, 16-22
(See also Miocene, Pliocene.)
Telegraph and telephone offices . . . . 6
Thermal metamorphism . . . . 13
Tilting of strata
8, 10, 17
. . 7, 24
Tony Creek, gold in
. . 37, 38
. . 13, 15
Tracks, roads, &c
. . 5, 6
Uplift of land (see Elevation).
9, 19, 22
2, 3, 10
Veins, metalliferous . . 1, 2, 4, 5, 14, 15, 24-36
„ ,, distribution and de-
scription of . . 24-34
„ „ general observations on 34-36
Von Haast, Julius . . . . . . 1, 7
Wanganui, Little : River, settlement, &c.
(see Little Wanganui).
Warping of strata
Weka Pass, limestone of
Zinc in ores
9, 10, 11-
25, 30, 35, 36
. . 13, 14
. . 2, 24
By Authority : John Mackay, Government Printer, Wellington.— 1910.